Merge branch 'youngyangyang04:master' into master

Author: janeyziqinglin

problems/0015.三数之和.md

@@ -345,6 +345,76 @@ var threeSum = function(nums) {
     return res
 };
 ```
+
+解法二：nSum通用解法。递归
+
+```js
+/**
+ *  nsum通用解法，支持2sum，3sum，4sum...等等
+ *  时间复杂度分析：
+ *  1. n = 2时，时间复杂度O(NlogN)，排序所消耗的时间。、
+ *  2. n > 2时，时间复杂度为O(N^n-1)，即N的n-1次方，至少是2次方，此时可省略排序所消耗的时间。举例：3sum为O(n^2)，4sum为O(n^3)
+ * @param {number[]} nums
+ * @return {number[][]}
+ */
+var threeSum = function (nums) {
+    // nsum通用解法核心方法
+    function nSumTarget(nums, n, start, target) {
+        // 前提：nums要先排序好
+        let res = [];
+        if (n === 2) {
+            res = towSumTarget(nums, start, target);
+        } else {
+            for (let i = start; i < nums.length; i++) {
+                // 递归求(n - 1)sum
+                let subRes = nSumTarget(
+                    nums,
+                    n - 1,
+                    i + 1,
+                    target - nums[i]
+                );
+                for (let j = 0; j < subRes.length; j++) {
+                    res.push([nums[i], ...subRes[j]]);
+                }
+                // 跳过相同元素
+                while (nums[i] === nums[i + 1]) i++;
+            }
+        }
+        return res;
+    }
+
+    function towSumTarget(nums, start, target) {
+        // 前提：nums要先排序好
+        let res = [];
+        let len = nums.length;
+        let left = start;
+        let right = len - 1;
+        while (left < right) {
+            let sum = nums[left] + nums[right];
+            if (sum < target) {
+                while (nums[left] === nums[left + 1]) left++;
+                left++;
+            } else if (sum > target) {
+                while (nums[right] === nums[right - 1]) right--;
+                right--;
+            } else {
+                // 相等
+                res.push([nums[left], nums[right]]);
+                // 跳过相同元素
+                while (nums[left] === nums[left + 1]) left++;
+                while (nums[right] === nums[right - 1]) right--;
+                left++;
+                right--;
+            }
+        }
+        return res;
+    }
+    nums.sort((a, b) => a - b);
+    // n = 3，此时求3sum之和
+    return nSumTarget(nums, 3, 0, 0);
+};
+```
+
 TypeScript:
 
 ```typescript

problems/0020.有效的括号.md

@@ -400,6 +400,37 @@ bool isValid(char * s){
     return !stackTop;
 }
 ```
+
+
+PHP:
+```php
+// https://www.php.net/manual/zh/class.splstack.php
+class Solution
+{
+    function isValid($s){
+        $stack = new SplStack();
+        for ($i = 0; $i < strlen($s); $i++) {
+            if ($s[$i] == "(") {
+                $stack->push(')');
+            } else if ($s[$i] == "{") {
+                $stack->push('}');
+            } else if ($s[$i] == "[") {
+                $stack->push(']');
+            // 2、遍历匹配过程中，发现栈内没有要匹配的字符 return false
+            // 3、遍历匹配过程中，栈已为空，没有匹配的字符了，说明右括号没有找到对应的左括号 return false
+            } else if ($stack->isEmpty() || $stack->top() != $s[$i]) {
+                return false;
+            } else {//$stack->top() == $s[$i]
+                $stack->pop();
+            }
+        }
+        // 1、遍历完，但是栈不为空,说明有相应的括号没有被匹配,return false
+        return $stack->isEmpty();
+    }
+}
+```
+
+
 Scala:
 ```scala
 object Solution {
@@ -422,5 +453,6 @@ object Solution {
   }
 }
 ```
+
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0189.旋转数组.md

@@ -7,6 +7,8 @@
 
 # 189. 旋转数组
 
+[力扣题目链接](https://leetcode.cn/problems/rotate-array/)
+
 给定一个数组，将数组中的元素向右移动 k 个位置，其中 k 是非负数。
 
 进阶：
@@ -160,6 +162,27 @@ var rotate = function (nums, k) {
 };
 ```
 
+## TypeScript
+
+```typescript
+function rotate(nums: number[], k: number): void {
+    const length: number = nums.length;
+    k %= length;
+    reverseByRange(nums, 0, length - 1);
+    reverseByRange(nums, 0, k - 1);
+    reverseByRange(nums, k, length - 1);
+};
+function reverseByRange(nums: number[], left: number, right: number): void {
+    while (left < right) {
+        const temp = nums[left];
+        nums[left] = nums[right];
+        nums[right] = temp;
+        left++;
+        right--;
+    }
+}
+```
+
 
 
 -----------------------

problems/0225.用队列实现栈.md

@@ -816,7 +816,6 @@ class MyStack {
 }
 ```
 Scala:
-
 使用两个队列模拟栈:
 ```scala
 import scala.collection.mutable
@@ -897,6 +896,86 @@ class MyStack() {
   def empty(): Boolean = {
     queue.isEmpty
   }
+  }
+```
+
+
+PHP
+> 双对列
+```php
+// SplQueue 类通过使用一个双向链表来提供队列的主要功能。(PHP 5 >= 5.3.0, PHP 7, PHP 8)
+// https://www.php.net/manual/zh/class.splqueue.php
+class MyStack {
+    public $queueMain; // 保存数据
+    public $queueTmp;  // 辅助作用
+
+    function __construct() {
+        $this->queueMain=new SplQueue();
+        $this->queueTmp=new SplQueue();
+    }
+    
+    // queueMain: 1,2,3 <= add
+    function push($x) {
+        $this->queueMain->enqueue($x);
+    }
+                                    
+    function pop() {
+       $qmSize = $this->queueMain->Count();
+       $qmSize --;
+       // queueMain: 3,2,1 => pop =>2,1 => add => 2,1 :queueTmp
+       while($qmSize --){
+           $this->queueTmp->enqueue($this->queueMain->dequeue());
+       }
+       // queueMain: 3
+       $val = $this->queueMain->dequeue();
+       // queueMain <= queueTmp 
+       $this->queueMain = $this->queueTmp;
+       // 清空queueTmp,下次使用 
+       $this->queueTmp = new SplQueue();
+       return $val;
+    }
+
+    function top() {
+        // 底层是双链表实现：从双链表的末尾查看节点
+        return $this->queueMain->top(); 
+    }
+
+    function empty() {
+        return $this->queueMain->isEmpty();
+    }
+}
+```
+> 单对列
+```php
+class MyStack {
+    public $queue;
+
+    function __construct() {
+        $this->queue=new SplQueue();
+    }
+    
+    function push($x) {
+        $this->queue->enqueue($x);
+    }
+                                 
+    function pop() {
+       $qmSize = $this->queue->Count();
+       $qmSize --;
+       //queue: 3,2,1 => pop =>2,1 => add => 2,1,3 :queue
+       while($qmSize --){
+           $this->queue->enqueue($this->queue->dequeue());
+       }
+       $val = $this->queue->dequeue();
+       return $val;
+    }
+
+    function top() {
+        return $this->queue->top(); 
+    }
+
+    function empty() {
+        return $this->queue->isEmpty();
+    }
 }
 ```
 -----------------------

problems/0232.用栈实现队列.md

@@ -495,6 +495,53 @@ void myQueueFree(MyQueue* obj) {
     obj->stackOutTop = 0;
 }
 ```
+
+
+PHP:
+```php
+// SplStack 类通过使用一个双向链表来提供栈的主要功能。[PHP 5 >= 5.3.0, PHP 7, PHP 8]
+// https://www.php.net/manual/zh/class.splstack.php
+class MyQueue {
+    // 双栈模拟队列：In栈存储数据；Out栈辅助处理
+    private $stackIn;
+    private $stackOut;
+    
+    function __construct() {
+        $this->stackIn = new SplStack();
+        $this->stackOut = new SplStack();
+    }
+
+    // In: 1 2 3  <= push  
+    function push($x) {
+        $this->stackIn->push($x);
+    }
+
+    function pop() {
+        $this->peek();
+        return $this->stackOut->pop();
+    }
+
+    function peek() {
+        if($this->stackOut->isEmpty()){
+            $this->shift();
+        }
+        return $this->stackOut->top();
+    }
+
+    function empty() {
+        return $this->stackOut->isEmpty() && $this->stackIn->isEmpty();
+    }
+
+    // 如果Out栈为空，把In栈数据压入Out栈
+    // In: 1 2 3 => pop    push => 1 2 3 :Out  
+    private function shift(){
+        while(!$this->stackIn->isEmpty()){
+            $this->stackOut->push($this->stackIn->pop());
+        }
+    }
+    }
+```
+
 Scala:
 ```scala
 class MyQueue() {
@@ -533,6 +580,7 @@ class MyQueue() {
   def empty(): Boolean = {
     stackIn.isEmpty && stackOut.isEmpty
   }
+
 }
 ```
 -----------------------

problems/0283.移动零.md

@@ -133,6 +133,27 @@ var moveZeroes = function(nums) {
 };
 ```
 
+TypeScript：
+
+```typescript
+function moveZeroes(nums: number[]): void {
+    const length: number = nums.length;
+    let slowIndex: number = 0,
+        fastIndex: number = 0;
+    while (fastIndex < length) {
+        if (nums[fastIndex] !== 0) {
+            nums[slowIndex++] = nums[fastIndex];
+        };
+        fastIndex++;
+    }
+    while (slowIndex < length) {
+        nums[slowIndex++] = 0;
+    }
+};
+```
+
+
+
 
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0509.斐波那契数.md

@@ -234,6 +234,7 @@ func fib(n int) int {
 }
 ```
 ### Javascript 
+解法一
 ```Javascript
 var fib = function(n) {
     let dp = [0, 1]
@@ -244,6 +245,23 @@ var fib = function(n) {
     return dp[n]
 };
 ```
+解法二：时间复杂度O(N)，空间复杂度O(1)
+```Javascript
+var fib = function(n) {
+    // 动规状态转移中，当前结果只依赖前两个元素的结果，所以只要两个变量代替dp数组记录状态过程。将空间复杂度降到O(1)
+    let pre1 = 1
+    let pre2 = 0
+    let temp
+    if (n === 0) return 0
+    if (n === 1) return 1
+    for(let i = 2; i <= n; i++) {
+        temp = pre1
+        pre1 = pre1 + pre2
+        pre2 = temp
+    }
+    return pre1
+};
+```
 
 TypeScript
 

problems/0541.反转字符串II.md

@@ -53,10 +53,10 @@ public:
             // 2. 剩余字符小于 2k 但大于或等于 k 个，则反转前 k 个字符
             if (i + k <= s.size()) {
                 reverse(s.begin() + i, s.begin() + i + k );
-                continue;
+            } else {
+                // 3. 剩余字符少于 k 个，则将剩余字符全部反转。
+                reverse(s.begin() + i, s.end());
             }
-            // 3. 剩余字符少于 k 个，则将剩余字符全部反转。
-            reverse(s.begin() + i, s.begin() + s.size());
         }
         return s;
     }