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feat: add solutions to lc problem: No.0218 (doocs#858)
No.0218.The Skyline Problem
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‎solution/0200-0299/0218.The Skyline Problem/README.md

Lines changed: 75 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -55,22 +55,93 @@
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<!-- 这里可写通用的实现逻辑 -->
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**方法一：扫描线+优先队列**
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记录下所有建筑物的左右边界线，升序排序之后得到序列 lines。对于每一个边界线 lines[i]，找出所有包含 lines[i] 的建筑物，并确保建筑物的左边界小于等于 lines[i]，右边界大于 lines[i]，则这些建筑物中高度最高的建筑物的高度就是该线轮廓点的高度。可以使用建筑物的高度构建优先队列（大根堆），同时需要注意高度相同的轮廓点需要合并为一个。
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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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from queue import PriorityQueue
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class Solution:
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def getSkyline(self, buildings: List[List[int]]) -> List[List[int]]:
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skys, lines, pq = [], [], PriorityQueue()
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for build in buildings:
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lines.extend([build[0], build[1]])
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lines.sort()
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city, n = 0, len(buildings)
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for line in lines:
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while city < n and buildings[city][0] <= line:
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pq.put([-buildings[city][2], buildings[city]
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[0], buildings[city][1]])
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city += 1
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while not pq.empty() and pq.queue[0][2] <= line:
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pq.get()
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high = 0
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if not pq.empty():
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high = -pq.queue[0][0]
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if len(skys) > 0 and skys[-1][1] == high:
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continue
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skys.append([line, high])
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return skys
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```
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### **Java**
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### **Go**
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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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```go
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type Matrix struct{ left, right, height int }
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type Queue []Matrix
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func (q Queue) Len() int { return len(q) }
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func (q Queue) Top() Matrix { return q[0] }
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func (q Queue) Swap(i, j int) { q[i], q[j] = q[j], q[i] }
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func (q Queue) Less(i, j int) bool { return q[i].height > q[j].height }
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func (q *Queue) Push(x interface{}) { *q = append(*q, x.(Matrix)) }
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func (q *Queue) Pop() interface{} {
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old, x := *q, (*q)[len(*q)-1]
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*q = old[:len(old)-1]
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return x
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}
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func getSkyline(buildings [][]int) [][]int {
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skys, lines, pq := make([][]int, 0), make([]int, 0), &Queue{}
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heap.Init(pq)
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for _, v := range buildings {
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lines = append(lines, v[0], v[1])
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}
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sort.Ints(lines)
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city, n := 0, len(buildings)
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for _, line := range lines {
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// 将所有符合条件的矩形加入队列
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for ; city < n && buildings[city][0] <= line && buildings[city][1] > line; city++ {
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v := Matrix{left: buildings[city][0], right: buildings[city][1], height: buildings[city][2]}
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heap.Push(pq, v)
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}
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// 从队列移除不符合条件的矩形
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for pq.Len() > 0 && pq.Top().right <= line {
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heap.Pop(pq)
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}
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high := 0
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// 队列为空说明是最右侧建筑物的终点，其轮廓点为 (line, 0)
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if pq.Len() != 0 {
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high = pq.Top().height
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}
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// 如果该点高度和前一个轮廓点一样的话，直接忽略
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if len(skys) > 0 && skys[len(skys)-1][1] == high {
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continue
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}
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skys = append(skys, []int{line, high})
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}
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return skys
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}
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```
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### **C++**

‎solution/0200-0299/0218.The Skyline Problem/README_EN.md

Lines changed: 72 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -55,13 +55,80 @@ Figure B shows the skyline formed by those buildings. The red points in figure B
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### **Python3**
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```python
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from queue import PriorityQueue
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class Solution:
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def getSkyline(self, buildings: List[List[int]]) -> List[List[int]]:
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skys, lines, pq = [], [], PriorityQueue()
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for build in buildings:
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lines.extend([build[0], build[1]])
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lines.sort()
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city, n = 0, len(buildings)
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for line in lines:
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while city < n and buildings[city][0] <= line:
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pq.put([-buildings[city][2], buildings[city]
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[0], buildings[city][1]])
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city += 1
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while not pq.empty() and pq.queue[0][2] <= line:
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pq.get()
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high = 0
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if not pq.empty():
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high = -pq.queue[0][0]
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if len(skys) > 0 and skys[-1][1] == high:
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continue
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skys.append([line, high])
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return skys
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```
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### **Java**
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```java
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### **Go**
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```go
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type Matrix struct{ left, right, height int }
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type Queue []Matrix
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func (q Queue) Len() int { return len(q) }
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func (q Queue) Top() Matrix { return q[0] }
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func (q Queue) Swap(i, j int) { q[i], q[j] = q[j], q[i] }
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func (q Queue) Less(i, j int) bool { return q[i].height > q[j].height }
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func (q *Queue) Push(x interface{}) { *q = append(*q, x.(Matrix)) }
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func (q *Queue) Pop() interface{} {
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old, x := *q, (*q)[len(*q)-1]
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*q = old[:len(old)-1]
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return x
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}
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func getSkyline(buildings [][]int) [][]int {
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skys, lines, pq := make([][]int, 0), make([]int, 0), &Queue{}
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heap.Init(pq)
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for _, v := range buildings {
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lines = append(lines, v[0], v[1])
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}
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sort.Ints(lines)
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city, n := 0, len(buildings)
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for _, line := range lines {
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// 将所有符合条件的矩形加入队列
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for ; city < n && buildings[city][0] <= line && buildings[city][1] > line; city++ {
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v := Matrix{left: buildings[city][0], right: buildings[city][1], height: buildings[city][2]}
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heap.Push(pq, v)
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}
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// 从队列移除不符合条件的矩形
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for pq.Len() > 0 && pq.Top().right <= line {
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heap.Pop(pq)
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}
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high := 0
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// 队列为空说明是最右侧建筑物的终点，其轮廓点为 (line, 0)
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if pq.Len() != 0 {
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high = pq.Top().height
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}
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// 如果该点高度和前一个轮廓点一样的话，直接忽略
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if len(skys) > 0 && skys[len(skys)-1][1] == high {
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continue
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}
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skys = append(skys, []int{line, high})
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}
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return skys
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}
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```
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### **C++**

‎solution/0200-0299/0218.The Skyline Problem/Solution.go

Lines changed: 45 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,45 @@
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type Matrix struct{ left, right, height int }
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type Queue []Matrix
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func (q Queue) Len() int { return len(q) }
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func (q Queue) Top() Matrix { return q[0] }
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func (q Queue) Swap(i, j int) { q[i], q[j] = q[j], q[i] }
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func (q Queue) Less(i, j int) bool { return q[i].height > q[j].height }
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func (q *Queue) Push(x interface{}) { *q = append(*q, x.(Matrix)) }
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func (q *Queue) Pop() interface{} {
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old, x := *q, (*q)[len(*q)-1]
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*q = old[:len(old)-1]
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return x
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}
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func getSkyline(buildings [][]int) [][]int {
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skys, lines, pq := make([][]int, 0), make([]int, 0), &Queue{}
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heap.Init(pq)
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for _, v := range buildings {
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lines = append(lines, v[0], v[1])
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}
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sort.Ints(lines)
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city, n := 0, len(buildings)
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for _, line := range lines {
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// 将所有符合条件的矩形加入队列
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for ; city < n && buildings[city][0] <= line && buildings[city][1] > line; city++ {
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v := Matrix{left: buildings[city][0], right: buildings[city][1], height: buildings[city][2]}
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heap.Push(pq, v)
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}
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// 从队列移除不符合条件的矩形
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for pq.Len() > 0 && pq.Top().right <= line {
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heap.Pop(pq)
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}
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high := 0
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// 队列为空说明是最右侧建筑物的终点，其轮廓点为 (line, 0)
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if pq.Len() != 0 {
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high = pq.Top().height
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}
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// 如果该点高度和前一个轮廓点一样的话，直接忽略
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if len(skys) > 0 && skys[len(skys)-1][1] == high {
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continue
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}
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skys = append(skys, []int{line, high})
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}
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return skys
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}

‎solution/0200-0299/0218.The Skyline Problem/Solution.py

Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
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from queue import PriorityQueue
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class Solution:
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def getSkyline(self, buildings: List[List[int]]) -> List[List[int]]:
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skys, lines, pq = [], [], PriorityQueue()
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for build in buildings:
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lines.extend([build[0], build[1]])
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lines.sort()
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city, n = 0, len(buildings)
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for line in lines:
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while city < n and buildings[city][0] <= line:
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pq.put([-buildings[city][2], buildings[city]
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[0], buildings[city][1]])
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city += 1
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while not pq.empty() and pq.queue[0][2] <= line:
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pq.get()
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high = 0
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if not pq.empty():
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high = -pq.queue[0][0]
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if len(skys) > 0 and skys[-1][1] == high:
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continue
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skys.append([line, high])
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return skys

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