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feat: add solutions to lc problem: No.0390
No.0390.Elimination Game
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‎solution/0300-0399/0390.Elimination Game/README.md

Lines changed: 95 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -29,22 +29,116 @@ n = 9,
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<!-- 这里可写通用的实现逻辑 -->
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用 `i` 记录该从左边还是右边进行删除。由于经过每轮删除过后都是一个等差数列，因此我们用 `a1`, `an` 记录首尾元素，`cnt` 记录数列元素个数，`step` 记录元素间的间隔，`step` 初始为 1。
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- 若从左边删除：
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- `a1` 变为 `a1 + step`
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- 若 `cnt` 为奇数个，`an` 变为 `an - step`，否则 `an` 不变
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- 若从右边删除：
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- `an` 变为 `an - step`
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- 若 `cnt` 为奇数个，`a1` 变为 `a1 + step`，否则 `a1` 不变
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每次经过一轮删除，数列元素个数 `cnt` 变为 `cnt >> 1`，元素间隔 `step` 变为 `step << 1`，`i` 自增 1。
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当元素个数剩下 1 个时，退出循环，返回 `a1` 即可。
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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
39-
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class Solution:
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def lastRemaining(self, n: int) -> int:
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a1, an = 1, n
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i, step, cnt = 0, 1, n
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while cnt > 1:
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if i % 2:
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an -= step
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if cnt % 2:
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a1 += step
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else:
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a1 += step
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if cnt % 2:
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an -= step
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cnt >>= 1
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step <<= 1
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i += 1
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return a1
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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 lastRemaining(int n) {
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int a1 = 1, an = n, step = 1;
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for (int i = 0, cnt = n; cnt > 1; cnt >>= 1, step <<= 1, ++i) {
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if (i % 2 == 1) {
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an -= step;
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if (cnt % 2 == 1) {
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a1 += step;
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}
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} else {
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a1 += step;
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if (cnt % 2 == 1) {
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an -= step;
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}
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}
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}
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return a1;
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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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int lastRemaining(int n) {
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int a1 = 1, an = n, step = 1;
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for (int i = 0, cnt = n; cnt > 1; cnt >>= 1, step <<= 1, ++i)
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{
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if (i % 2)
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{
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an -= step;
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if (cnt % 2) a1 += step;
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}
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else
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{
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a1 += step;
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if (cnt % 2) an -= step;
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}
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}
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return a1;
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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 lastRemaining(n int) int {
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a1, an, step := 1, n, 1
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for i, cnt := 0, n; cnt > 1; cnt, step, i = cnt>>1, step<<1, i+1 {
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if i%2 == 1 {
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an -= step
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if cnt%2 == 1 {
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a1 += step
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}
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} else {
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a1 += step
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if cnt%2 == 1 {
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an -= step
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}
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}
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}
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return a1
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}
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```
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### **...**

‎solution/0300-0399/0390.Elimination Game/README_EN.md

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Original file line numberDiff line numberDiff line change
@@ -48,13 +48,94 @@ arr = [6]
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### **Python3**
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```python
51-
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class Solution:
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def lastRemaining(self, n: int) -> int:
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a1, an = 1, n
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i, step, cnt = 0, 1, n
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while cnt > 1:
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if i % 2:
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an -= step
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if cnt % 2:
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a1 += step
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else:
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a1 += step
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if cnt % 2:
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an -= step
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cnt >>= 1
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step <<= 1
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i += 1
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return a1
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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 lastRemaining(int n) {
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int a1 = 1, an = n, step = 1;
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for (int i = 0, cnt = n; cnt > 1; cnt >>= 1, step <<= 1, ++i) {
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if (i % 2 == 1) {
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an -= step;
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if (cnt % 2 == 1) {
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a1 += step;
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}
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} else {
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a1 += step;
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if (cnt % 2 == 1) {
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an -= step;
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}
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}
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}
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return a1;
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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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int lastRemaining(int n) {
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int a1 = 1, an = n, step = 1;
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for (int i = 0, cnt = n; cnt > 1; cnt >>= 1, step <<= 1, ++i)
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{
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if (i % 2)
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{
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an -= step;
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if (cnt % 2) a1 += step;
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}
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else
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{
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a1 += step;
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if (cnt % 2) an -= step;
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}
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}
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return a1;
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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 lastRemaining(n int) int {
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a1, an, step := 1, n, 1
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for i, cnt := 0, n; cnt > 1; cnt, step, i = cnt>>1, step<<1, i+1 {
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if i%2 == 1 {
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an -= step
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if cnt%2 == 1 {
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a1 += step
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}
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} else {
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a1 += step
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if cnt%2 == 1 {
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an -= step
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}
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}
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}
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return a1
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}
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```
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### **...**

‎solution/0300-0399/0390.Elimination Game/Solution.cpp

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,20 @@
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class Solution {
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public:
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int lastRemaining(int n) {
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int a1 = 1, an = n, step = 1;
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for (int i = 0, cnt = n; cnt > 1; cnt >>= 1, step <<= 1, ++i)
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{
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if (i % 2)
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{
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an -= step;
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if (cnt % 2) a1 += step;
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}
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else
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{
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a1 += step;
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if (cnt % 2) an -= step;
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}
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}
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return a1;
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}
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};

‎solution/0300-0399/0390.Elimination Game/Solution.go

Lines changed: 17 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,17 @@
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func lastRemaining(n int) int {
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a1, an, step := 1, n, 1
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for i, cnt := 0, n; cnt > 1; cnt, step, i = cnt>>1, step<<1, i+1 {
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if i%2 == 1 {
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an -= step
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if cnt%2 == 1 {
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a1 += step
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}
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} else {
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a1 += step
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if cnt%2 == 1 {
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an -= step
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}
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}
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}
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return a1
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}

‎solution/0300-0399/0390.Elimination Game/Solution.java

Lines changed: 19 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,19 @@
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class Solution {
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public int lastRemaining(int n) {
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int a1 = 1, an = n, step = 1;
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for (int i = 0, cnt = n; cnt > 1; cnt >>= 1, step <<= 1, ++i) {
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if (i % 2 == 1) {
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an -= step;
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if (cnt % 2 == 1) {
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a1 += step;
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}
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} else {
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a1 += step;
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if (cnt % 2 == 1) {
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an -= step;
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}
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}
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}
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return a1;
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}
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}

‎solution/0300-0399/0390.Elimination Game/Solution.py

Lines changed: 17 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,17 @@
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class Solution:
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def lastRemaining(self, n: int) -> int:
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a1, an = 1, n
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i, step, cnt = 0, 1, n
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while cnt > 1:
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if i % 2:
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an -= step
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if cnt % 2:
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a1 += step
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else:
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a1 += step
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if cnt % 2:
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an -= step
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cnt >>= 1
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step <<= 1
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i += 1
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return a1

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