Merge branch 'master' of github.com:youngyangyang04/leetcode-master

README.md

@@ -523,6 +523,10 @@
 
 [点此这里](https://github.com/youngyangyang04/leetcode-master/graphs/contributors)查看LeetCode-Master的所有贡献者。感谢他们补充了LeetCode-Master的其他语言版本，让更多的读者收益于此项目。
 
+# Star 趋势
+
+[![Star History Chart](https://api.star-history.com/svg?repos=youngyangyang04/leetcode-master&type=Date)](https://star-history.com/#youngyangyang04/leetcode-master&Date)
+
 # 关于作者
 
 大家好，我是程序员Carl，哈工大师兄，《代码随想录》作者，先后在腾讯和百度从事后端技术研发，CSDN博客专家。对算法和C++后端技术有一定的见解，利用工作之余重新刷leetcode。 

problems/0027.移除元素.md

@@ -183,28 +183,24 @@ class Solution {
 
 Python：
 
-```python
+```python3
 class Solution:
-    """双指针法
-    时间复杂度：O(n)
-    空间复杂度：O(1)
-    """
-
-    @classmethod
-    def removeElement(cls, nums: List[int], val: int) -> int:
-        fast = slow = 0
-
-        while fast < len(nums):
-
-            if nums[fast] != val:
-                nums[slow] = nums[fast]
-                slow += 1
-
-            # 当 fast 指针遇到要删除的元素时停止赋值
-            # slow 指针停止移动, fast 指针继续前进
-            fast += 1
-
-        return slow
+    def removeElement(self, nums: List[int], val: int) -> int:
+        if nums is None or len(nums)==0: 
+            return 0 
+        l=0
+        r=len(nums)-1
+        while l<r: 
+            while(l<r and nums[l]!=val):
+                l+=1
+            while(l<r and nums[r]==val):
+                r-=1
+            nums[l], nums[r]=nums[r], nums[l]
+        print(nums)
+        if nums[l]==val: 
+            return l 
+        else: 
+            return l+1
 ```
 
 

problems/0028.实现strStr.md

@@ -685,7 +685,21 @@ class Solution {
 ```
 
 Python3：
-
+```python
+//暴力解法：
+class Solution(object):
+    def strStr(self, haystack, needle):
+        """
+        :type haystack: str
+        :type needle: str
+        :rtype: int
+        """
+        m,n=len(haystack),len(needle)
+        for i in range(m):
+            if haystack[i:i+n]==needle:
+                return i
+        return -1    
+```	
 ```python
 // 方法一
 class Solution:

problems/0034.在排序数组中查找元素的第一个和最后一个位置.md

@@ -7,7 +7,8 @@
 
 # 34. 在排序数组中查找元素的第一个和最后一个位置
 
-[题目链接](https://leetcode.cn/problems/find-first-and-last-position-of-element-in-sorted-array/)
+[力扣链接](https://leetcode.cn/problems/find-first-and-last-position-of-element-in-sorted-array/)
+
 
 给定一个按照升序排列的整数数组 nums，和一个目标值 target。找出给定目标值在数组中的开始位置和结束位置。
 

problems/0046.全排列.md

@@ -359,6 +359,36 @@ function permute(nums: number[]): number[][] {
 };
 ```
 
+### Rust
+
+```Rust
+impl Solution {
+    fn backtracking(result: &mut Vec<Vec<i32>>, path: &mut Vec<i32>, nums: &Vec<i32>, used: &mut Vec<bool>) {
+        let len = nums.len();
+        if path.len() == len {
+            result.push(path.clone());
+            return;
+        }
+        for i in 0..len {
+            if used[i] == true { continue; }
+            used[i] = true;
+            path.push(nums[i]);
+            Self::backtracking(result, path, nums, used);
+            path.pop();
+            used[i] = false;
+        }
+    }
+
+    pub fn permute(nums: Vec<i32>) -> Vec<Vec<i32>> {
+        let mut result: Vec<Vec<i32>> = Vec::new();
+        let mut path: Vec<i32> = Vec::new();
+        let mut used = vec![false; nums.len()];
+        Self::backtracking(&mut result, &mut path, &nums, &mut used);
+        result
+    }
+}
+```
+
 ### C
 
 ```c

problems/0052.N皇后II.md

@@ -144,7 +144,61 @@ var totalNQueens = function(n) {
 };
 ```
 
+TypeScript：
+
+```typescript
+// 0-该格为空，1-该格有皇后
+type GridStatus = 0 | 1;
+function totalNQueens(n: number): number {
+    let resCount: number = 0;
+    const chess: GridStatus[][] = new Array(n).fill(0)
+        .map(_ => new Array(n).fill(0));
+    backTracking(chess, n, 0);
+    return resCount;
+    function backTracking(chess: GridStatus[][], n: number, startRowIndex: number): void {
+        if (startRowIndex === n) {
+            resCount++;
+            return;
+        }
+        for (let j = 0; j < n; j++) {
+            if (checkValid(chess, startRowIndex, j, n) === true) {
+                chess[startRowIndex][j] = 1;
+                backTracking(chess, n, startRowIndex + 1);
+                chess[startRowIndex][j] = 0;
+            }
+        }
+    }
+};
+function checkValid(chess: GridStatus[][], i: number, j: number, n: number): boolean {
+    // 向上纵向检查
+    let tempI: number = i - 1,
+        tempJ: number = j;
+    while (tempI >= 0) {
+        if (chess[tempI][tempJ] === 1) return false;
+        tempI--;
+    }
+    // 斜向左上检查
+    tempI = i - 1;
+    tempJ = j - 1;
+    while (tempI >= 0 && tempJ >= 0) {
+        if (chess[tempI][tempJ] === 1) return false;
+        tempI--;
+        tempJ--;
+    }
+    // 斜向右上检查
+    tempI = i - 1;
+    tempJ = j + 1;
+    while (tempI >= 0 && tempJ < n) {
+        if (chess[tempI][tempJ] === 1) return false;
+        tempI--;
+        tempJ++;
+    }
+    return true;
+}
+```
+
 C
+
 ```c
 //path[i]为在i行，path[i]列上存在皇后
 int *path;

problems/0054.螺旋矩阵.md

@@ -171,6 +171,30 @@ class Solution:
 
         return res
 ```
-
+```python3
+class Solution:
+    def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
+        r=len(matrix)
+        if r == 0 or len(matrix[0])==0: 
+            return []
+        c=len(matrix[0])
+        res=matrix[0]
+        
+        if r>1: 
+            for i in range (1,r):
+                res.append(matrix[i][c-1])
+            for j in range(c-2, -1, -1):
+                res.append(matrix[r-1][j])
+            if c>1:    
+                for i in range(r-2, 0, -1):    
+                    res.append(matrix[i][0])
+                    
+        M=[]
+        for k in range(1, r-1):
+            e=matrix[k][1:-1]
+            M.append(e)
+            
+        return res+self.spiralOrder(M) 
+```        
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0134.加油站.md

@@ -471,5 +471,73 @@ int canCompleteCircuit(int* gas, int gasSize, int* cost, int costSize){
 }
 ```
 
+### Scala
+
+暴力解法:
+
+```scala
+object Solution {
+  def canCompleteCircuit(gas: Array[Int], cost: Array[Int]): Int = {
+    for (i <- cost.indices) {
+      var rest = gas(i) - cost(i)
+      var index = (i + 1) % cost.length // index为i的下一个节点
+      while (rest > 0 && i != index) {
+        rest += (gas(index) - cost(index))
+        index = (index + 1) % cost.length
+      }
+      if (rest >= 0 && index == i) return i
+    }
+    -1
+  }
+}
+```
+
+贪心算法，方法一:
+
+```scala
+object Solution {
+  def canCompleteCircuit(gas: Array[Int], cost: Array[Int]): Int = {
+    var curSum = 0
+    var min = Int.MaxValue
+    for (i <- gas.indices) {
+      var rest = gas(i) - cost(i)
+      curSum += rest
+      min = math.min(min, curSum)
+    }
+    if (curSum < 0) return -1 // 情况1: gas的总和小于cost的总和，不可能到达终点
+    if (min >= 0) return 0 // 情况2: 最小值>=0，从0号出发可以直接到达
+    // 情况3: min为负值，从后向前看，能把min填平的节点就是出发节点
+    for (i <- gas.length - 1 to 0 by -1) {
+      var rest = gas(i) - cost(i)
+      min += rest
+      if (min >= 0) return i
+    }
+    -1
+  }
+}
+```
+
+贪心算法，方法二:
+
+```scala
+object Solution {
+  def canCompleteCircuit(gas: Array[Int], cost: Array[Int]): Int = {
+    var curSum = 0
+    var totalSum = 0
+    var start = 0
+    for (i <- gas.indices) {
+      curSum += (gas(i) - cost(i))
+      totalSum += (gas(i) - cost(i))
+      if (curSum < 0) {
+        start = i + 1 // 起始位置更新
+        curSum = 0  // curSum从0开始
+      }
+    }
+    if (totalSum < 0) return -1 // 说明怎么走不可能跑一圈
+    start
+  }
+}
+```
+
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0209.长度最小的子数组.md

@@ -179,8 +179,27 @@ class Solution:
                 index += 1
         return 0 if res==float("inf") else res
 ```
-
-
+```python3
+#滑动窗口
+class Solution:
+    def minSubArrayLen(self, target: int, nums: List[int]) -> int:
+        if nums is None or len(nums)==0: 
+            return 0 
+        lenf=len(nums)+1
+        total=0
+        i=j=0
+        while (j<len(nums)):
+            total=total+nums[j]
+            j+=1
+            while (total>=target):
+                lenf=min(lenf,j-i)
+                total=total-nums[i]
+                i+=1
+        if lenf==len(nums)+1:
+            return 0
+        else: 
+            return lenf
+```
 Go：
 ```go
 func minSubArrayLen(target int, nums []int) int {

problems/0234.回文链表.md

@@ -218,59 +218,41 @@ class Solution {
 ```python
 #数组模拟
 class Solution:
-    def isPalindrome(self, head: ListNode) -> bool:
-        length = 0
-        tmp = head
-        while tmp: #求链表长度
-            length += 1
-            tmp = tmp.next
-        
-        result = [0] * length
-        tmp = head
-        index = 0
-        while tmp: #链表元素加入数组
-            result[index] = tmp.val
-            index += 1
-            tmp = tmp.next
-        
-        i, j = 0, length - 1
-        while i < j: # 判断回文
-            if result[i] != result[j]:
+    def isPalindrome(self, head: Optional[ListNode]) -> bool:
+        list=[]
+        while head: 
+            list.append(head.val)
+            head=head.next
+        l,r=0, len(list)-1
+        while l<=r: 
+            if list[l]!=list[r]:
                 return False
-            i += 1
-            j -= 1
-        return True
-        
+            l+=1
+            r-=1
+        return True   
+      
 #反转后半部分链表
 class Solution:
-    def isPalindrome(self, head: ListNode) -> bool:
-        if head == None or head.next == None:
-            return True
-        slow, fast = head, head
-        while fast and fast.next:
-            pre = slow
-            slow = slow.next
-            fast = fast.next.next
-        
-        pre.next = None # 分割链表
-        cur1 = head # 前半部分
-        cur2 = self.reverseList(slow) # 反转后半部分，总链表长度如果是奇数，cur2比cur1多一个节点
-        while cur1:
-            if cur1.val != cur2.val:
-                return False
-            cur1 = cur1.next
-            cur2 = cur2.next
-        return True
+    def isPalindrome(self, head: Optional[ListNode]) -> bool:
+        fast = slow = head
 
-    def reverseList(self, head: ListNode) -> ListNode:
-        cur = head   
-        pre = None
-        while(cur!=None):
-            temp = cur.next # 保存一下cur的下一个节点
-            cur.next = pre # 反转
-            pre = cur
-            cur = temp
-        return pre
+        # find mid point which including (first) mid point into the first half linked list
+        while fast and fast.next:
+            fast = fast.next.next
+            slow = slow.next
+        node = None
+
+        # reverse second half linked list
+        while slow:
+            slow.next, slow, node = node, slow.next, slow
+
+        # compare reversed and original half; must maintain reversed linked list is shorter than 1st half
+        while node:
+            if node.val != head.val:
+                return False
+            node = node.next
+            head = head.next
+        return True
 ```
 
 ### Go

problems/0494.目标和.md

@@ -213,6 +213,7 @@ public:
         if (abs(S) > sum) return 0; // 此时没有方案
         if ((S + sum) % 2 == 1) return 0; // 此时没有方案
         int bagSize = (S + sum) / 2;
+	if (bagsize < 0) return 0;
         vector<int> dp(bagSize + 1, 0);
         dp[0] = 1;
         for (int i = 0; i < nums.size(); i++) {

problems/0617.合并二叉树.md

@@ -262,10 +262,10 @@ class Solution {
         if (root1 == null) return root2;
         if (root2 == null) return root1;
 
-        TreeNode newRoot = new TreeNode(root1.val + root2.val);
-        newRoot.left = mergeTrees(root1.left,root2.left);
-        newRoot.right = mergeTrees(root1.right,root2.right);
-        return newRoot;
+        root1.val += root2.val;
+        root1.left = mergeTrees(root1.left,root2.left);
+        root1.right = mergeTrees(root1.right,root2.right);
+        return root1;
     }
 }
 ```

problems/0704.二分查找.md

@@ -220,19 +220,21 @@ class Solution:
 
 （版本二）左闭右开区间
 
-```python
-class Solution:
+```class Solution:
     def search(self, nums: List[int], target: int) -> int:
-        left,right  =0, len(nums)
-        while left < right:
-            mid = (left + right) // 2
-            if nums[mid] < target:
-                left = mid+1
-            elif nums[mid] > target:
-                right = mid
+        if nums is None or len(nums)==0:
+            return -1
+        l=0
+        r=len(nums)-1
+        while (l<=r):
+            m = round(l+(r-l)/2)
+            if nums[m] == target:
+                return m     
+            elif nums[m] > target:
+                r=m-1
             else:
-                return mid
-        return -1
+                l=m+1
+        return -1 
 ```
 
 **Go：**

problems/0925.长按键入.md

@@ -129,29 +129,21 @@ class Solution {
 ```
 ### Python
 ```python
-class Solution:
-    def isLongPressedName(self, name: str, typed: str) -> bool:
-        i, j = 0, 0
-        m, n = len(name) , len(typed)
-        while i< m and j < n:
-            if name[i] == typed[j]: # 相同时向后匹配
-                i += 1
-                j += 1
-            else: # 不相同
-                if j == 0: return False # 如果第一位不相同，直接返回false
-                # 判断边界为n-1,若为n会越界,例如name:"kikcxmvzi" typed:"kiikcxxmmvvzzz"
-                while j < n - 1  and typed[j] == typed[j-1]: j += 1
-                if name[i] == typed[j]:
-                    i += 1
-                    j += 1
-                else: return False
-        # 说明name没有匹配完
-        if i < m: return False
-        # 说明type没有匹配完
-        while j < n:
-            if typed[j] == typed[j-1]: j += 1
-            else: return False
-        return True
+        i = j = 0
+        while(i<len(name) and j<len(typed)):
+        # If the current letter matches, move as far as possible
+            if typed[j]==name[i]:
+                while j+1<len(typed) and typed[j]==typed[j+1]:
+                    j+=1
+                    # special case when there are consecutive repeating letters
+                    if i+1<len(name) and name[i]==name[i+1]:
+                        i+=1
+                else:
+                    j+=1
+                    i+=1
+            else:
+                return False
+        return i == len(name) and j==len(typed)
 ```
 
 ### Go

problems/0977.有序数组的平方.md

@@ -41,6 +41,15 @@ public:
     }
 };
 ```
+```python3
+class Solution:
+    def sortedSquares(self, nums: List[int]) -> List[int]:
+        res=[]
+        for num in nums: 
+            res.append(num**2)
+        return sorted(res)   
+```	
+        
 
 这个时间复杂度是 O(n + nlogn)， 可以说是O(nlogn)的时间复杂度，但为了和下面双指针法算法时间复杂度有鲜明对比，我记为 O(n + nlog n)。
 

problems/1005.K次取反后最大化的数组和.md

@@ -289,6 +289,28 @@ function largestSumAfterKNegations(nums: number[], k: number): number {
 };
 ```
 
+### Scala
+
+```scala
+object Solution {
+  def largestSumAfterKNegations(nums: Array[Int], k: Int): Int = {
+    var num = nums.sortWith(math.abs(_) > math.abs(_))
+
+    var kk = k // 因为k是不可变量，所以要赋值给一个可变量
+    for (i <- num.indices) {
+      if (num(i) < 0 && kk > 0) {
+        num(i) *= -1 // 取反
+        kk -= 1
+      }
+    }
+
+    // kk对2取余，结果为0则为偶数不需要取反，结果为1为奇数，只需要对最后的数字进行反转就可以
+    if (kk % 2 == 1) num(num.size - 1) *= -1
+
+    num.sum // 最后返回数字的和
+  }
+}
+```
 
 
 

problems/qita/server.md

@@ -108,7 +108,7 @@ https://github.com/youngyangyang04/fileHttpServer
 
 如果你有一个服务器，那就是独立的一台电脑，你怎么霍霍就怎么霍霍，而且一年都不用关机的，可以一直跑你的任务，和你本地电脑也完全隔离。
 
-更方便的是，你目前系统假如是centos，想做一个实验需要在unbantu上，如果是云服务器，更换系统就是在 后台点一下，一键重装，云厂商基本都是支持所有系统一件安装的。
+更方便的是，你目前系统假如是CentOS，想做一个实验需要在Ubuntu上，如果是云服务器，更换系统就是在 后台点一下，一键重装，云厂商基本都是支持所有系统一件安装的。
 
 我们平时自己玩linux经常是配各种环境，然后这个linux就被自己玩坏了（一般都是毫无节制使用root权限导致的），总之就是环境配不起来了，基本就要重装了。
 

problems/面试题02.07.链表相交.md

@@ -160,6 +160,8 @@ class Solution:
         那么，只要其中一个链表走完了，就去走另一条链表的路。如果有交点，他们最终一定会在同一个
         位置相遇
         """
+        if headA is None or headB is None: 
+            return None
         cur_a, cur_b = headA, headB     # 用两个指针代替a和b