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feat: add solutions to lc problem: No.2015
No.2015.Average Height of Buildings in Each Segment
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‎solution/2000-2099/2015.Average Height of Buildings in Each Segment/README.md

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@@ -77,22 +77,153 @@
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<!-- 这里可写通用的实现逻辑 -->
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**方法一：差分有序哈希表**
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我们利用差分思想，使用有序哈希表 `height` 记录每个位置的高度变化，`cnt` 记录建筑物的数量变化。对有序哈希表求前缀和，即可得到每个位置的高度和建筑物数量。
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最后遍历有序哈希表，对于每个位置，如果高度和建筑物数量都不为 0，则说明该位置有建筑物，判断此时的建筑物是否与上个建筑物的平均高度相同，如果相同，则合并，否则加入结果集。
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时间复杂度为 $O(n\log n)$，其中 $n$ 为建筑物数量。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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class Solution:
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def averageHeightOfBuildings(self, buildings: List[List[int]]) -> List[List[int]]:
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height = defaultdict(int)
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cnt = defaultdict(int)
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for s, e, h in buildings:
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cnt[s] += 1
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cnt[e] -= 1
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height[s] += h
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height[e] -= h
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ans = []
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i = h = n = 0
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for j in sorted(cnt.keys()):
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if n:
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t = [i, j, h // n]
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if ans and ans[-1][1] == i and ans[-1][2] == t[-1]:
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ans[-1][1] = j
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else:
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ans.append(t)
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i = j
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h += height[j]
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n += cnt[j]
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return ans
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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class Solution {
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public int[][] averageHeightOfBuildings(int[][] buildings) {
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TreeMap<Integer, Integer> height = new TreeMap<>();
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TreeMap<Integer, Integer> cnt = new TreeMap<>();
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for (var v : buildings) {
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int s = v[0], e = v[1], h = v[2];
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cnt.put(s, cnt.getOrDefault(s, 0) + 1);
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cnt.put(e, cnt.getOrDefault(e, 0) - 1);
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height.put(s, height.getOrDefault(s, 0) + h);
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height.put(e, height.getOrDefault(e, 0) - h);
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}
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int i = 0, h = 0, n = 0;
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List<int[]> res = new ArrayList<>();
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for (int j : cnt.keySet()) {
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if (n > 0) {
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int[] t = new int[] {i, j, h / n};
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int k = res.size() - 1;
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if (k >= 0 && res.get(k)[1] == i && res.get(k)[2] == t[2]) {
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res.get(k)[1] = j;
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} else {
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res.add(t);
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}
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}
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h += height.get(j);
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n += cnt.get(j);
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i = j;
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}
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int[][] ans = new int[res.size()][3];
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for (i = 0; i < ans.length; ++i) {
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ans[i] = res.get(i);
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}
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return ans;
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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vector<vector<int>> averageHeightOfBuildings(vector<vector<int>>& buildings) {
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map<int, int> height, cnt;
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for (auto& v : buildings) {
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int s = v[0], e = v[1], h = v[2];
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cnt[s]++, cnt[e]--;
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height[s] += h, height[e] -= h;
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}
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vector<vector<int>> ans;
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int i = 0, h = 0, n = 0;
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for (auto& [j, _] : cnt) {
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if (n) {
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vector<int> t = {i, j, h / n};
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if (ans.size() && ans.back()[1] == i && ans.back()[2] == t[2]) {
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ans.back()[1] = j;
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} else {
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ans.push_back(t);
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}
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}
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i = j;
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h += height[j];
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n += cnt[j];
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}
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return ans;
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}
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};
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```
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### **Go**
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```go
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func averageHeightOfBuildings(buildings [][]int) [][]int {
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height := make(map[int]int)
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cnt := make(map[int]int)
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for _, v := range buildings {
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s, e, h := v[0], v[1], v[2]
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cnt[s]++
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cnt[e]--
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height[s] += h
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height[e] -= h
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}
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keys := make([]int, len(cnt))
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for k := range cnt {
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keys = append(keys, k)
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}
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sort.Ints(keys)
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i, h, n := 0, 0, 0
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ans := [][]int{}
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for _, j := range keys {
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if n > 0 {
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t := []int{i, j, h / n}
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if len(ans) > 0 && ans[len(ans)-1][1] == i && ans[len(ans)-1][2] == t[2] {
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ans[len(ans)-1][1] = j
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} else {
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ans = append(ans, t)
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}
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}
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i = j
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h += height[j]
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n += cnt[j]
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}
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return ans
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}
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```
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### **...**

‎solution/2000-2099/2015.Average Height of Buildings in Each Segment/README_EN.md

Lines changed: 124 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -79,13 +79,136 @@ We cannot group the segments together because an empty space with no buildings s
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### **Python3**
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```python
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class Solution:
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def averageHeightOfBuildings(self, buildings: List[List[int]]) -> List[List[int]]:
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height = defaultdict(int)
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cnt = defaultdict(int)
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for s, e, h in buildings:
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cnt[s] += 1
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cnt[e] -= 1
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height[s] += h
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height[e] -= h
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ans = []
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i = h = n = 0
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for j in sorted(cnt.keys()):
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if n:
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t = [i, j, h // n]
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if ans and ans[-1][1] == i and ans[-1][2] == t[-1]:
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ans[-1][1] = j
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else:
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ans.append(t)
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i = j
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h += height[j]
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n += cnt[j]
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return ans
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```
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### **Java**
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```java
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class Solution {
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public int[][] averageHeightOfBuildings(int[][] buildings) {
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TreeMap<Integer, Integer> height = new TreeMap<>();
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TreeMap<Integer, Integer> cnt = new TreeMap<>();
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for (var v : buildings) {
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int s = v[0], e = v[1], h = v[2];
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cnt.put(s, cnt.getOrDefault(s, 0) + 1);
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cnt.put(e, cnt.getOrDefault(e, 0) - 1);
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height.put(s, height.getOrDefault(s, 0) + h);
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height.put(e, height.getOrDefault(e, 0) - h);
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}
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int i = 0, h = 0, n = 0;
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List<int[]> res = new ArrayList<>();
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for (int j : cnt.keySet()) {
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if (n > 0) {
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int[] t = new int[] {i, j, h / n};
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int k = res.size() - 1;
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if (k >= 0 && res.get(k)[1] == i && res.get(k)[2] == t[2]) {
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res.get(k)[1] = j;
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} else {
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res.add(t);
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}
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}
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h += height.get(j);
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n += cnt.get(j);
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i = j;
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}
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int[][] ans = new int[res.size()][3];
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for (i = 0; i < ans.length; ++i) {
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ans[i] = res.get(i);
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}
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return ans;
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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vector<vector<int>> averageHeightOfBuildings(vector<vector<int>>& buildings) {
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map<int, int> height, cnt;
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for (auto& v : buildings) {
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int s = v[0], e = v[1], h = v[2];
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cnt[s]++, cnt[e]--;
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height[s] += h, height[e] -= h;
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}
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vector<vector<int>> ans;
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int i = 0, h = 0, n = 0;
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for (auto& [j, _] : cnt) {
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if (n) {
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vector<int> t = {i, j, h / n};
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if (ans.size() && ans.back()[1] == i && ans.back()[2] == t[2]) {
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ans.back()[1] = j;
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} else {
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ans.push_back(t);
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}
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}
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i = j;
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h += height[j];
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n += cnt[j];
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}
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return ans;
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}
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};
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```
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### **Go**
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```go
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func averageHeightOfBuildings(buildings [][]int) [][]int {
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height := make(map[int]int)
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cnt := make(map[int]int)
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for _, v := range buildings {
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s, e, h := v[0], v[1], v[2]
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cnt[s]++
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cnt[e]--
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height[s] += h
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height[e] -= h
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}
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keys := make([]int, len(cnt))
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for k := range cnt {
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keys = append(keys, k)
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}
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sort.Ints(keys)
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i, h, n := 0, 0, 0
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ans := [][]int{}
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for _, j := range keys {
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if n > 0 {
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t := []int{i, j, h / n}
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if len(ans) > 0 && ans[len(ans)-1][1] == i && ans[len(ans)-1][2] == t[2] {
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ans[len(ans)-1][1] = j
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} else {
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ans = append(ans, t)
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}
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}
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i = j
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h += height[j]
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n += cnt[j]
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}
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return ans
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}
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```
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### **...**

‎solution/2000-2099/2015.Average Height of Buildings in Each Segment/Solution.cpp

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class Solution {
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public:
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vector<vector<int>> averageHeightOfBuildings(vector<vector<int>>& buildings) {
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map<int, int> height, cnt;
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for (auto& v : buildings) {
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int s = v[0], e = v[1], h = v[2];
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cnt[s]++, cnt[e]--;
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height[s] += h, height[e] -= h;
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}
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vector<vector<int>> ans;
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int i = 0, h = 0, n = 0;
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for (auto& [j, _] : cnt) {
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if (n) {
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vector<int> t = {i, j, h / n};
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if (ans.size() && ans.back()[1] == i && ans.back()[2] == t[2]) {
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ans.back()[1] = j;
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} else {
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ans.push_back(t);
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}
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}
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i = j;
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h += height[j];
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n += cnt[j];
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}
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return ans;
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}
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};

‎solution/2000-2099/2015.Average Height of Buildings in Each Segment/Solution.go

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func averageHeightOfBuildings(buildings [][]int) [][]int {
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height := make(map[int]int)
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cnt := make(map[int]int)
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for _, v := range buildings {
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s, e, h := v[0], v[1], v[2]
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cnt[s]++
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cnt[e]--
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height[s] += h
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height[e] -= h
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}
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keys := make([]int, len(cnt))
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for k := range cnt {
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keys = append(keys, k)
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}
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sort.Ints(keys)
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i, h, n := 0, 0, 0
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ans := [][]int{}
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for _, j := range keys {
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if n > 0 {
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t := []int{i, j, h / n}
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if len(ans) > 0 && ans[len(ans)-1][1] == i && ans[len(ans)-1][2] == t[2] {
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ans[len(ans)-1][1] = j
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} else {
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ans = append(ans, t)
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}
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}
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i = j
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h += height[j]
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n += cnt[j]
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}
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return ans
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}

‎solution/2000-2099/2015.Average Height of Buildings in Each Segment/Solution.java

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class Solution {
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public int[][] averageHeightOfBuildings(int[][] buildings) {
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TreeMap<Integer, Integer> height = new TreeMap<>();
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TreeMap<Integer, Integer> cnt = new TreeMap<>();
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for (var v : buildings) {
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int s = v[0], e = v[1], h = v[2];
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cnt.put(s, cnt.getOrDefault(s, 0) + 1);
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cnt.put(e, cnt.getOrDefault(e, 0) - 1);
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height.put(s, height.getOrDefault(s, 0) + h);
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height.put(e, height.getOrDefault(e, 0) - h);
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}
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int i = 0, h = 0, n = 0;
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List<int[]> res = new ArrayList<>();
14+
for (int j : cnt.keySet()) {
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if (n > 0) {
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int[] t = new int[] {i, j, h / n};
17+
int k = res.size() - 1;
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if (k >= 0 && res.get(k)[1] == i && res.get(k)[2] == t[2]) {
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res.get(k)[1] = j;
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} else {
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res.add(t);
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}
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}
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h += height.get(j);
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n += cnt.get(j);
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i = j;
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}
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int[][] ans = new int[res.size()][3];
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for (i = 0; i < ans.length; ++i) {
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ans[i] = res.get(i);
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}
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return ans;
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}
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}

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