Merge branch 'youngyangyang04:master' into master

problems/0102.二叉树的层序遍历.md

@@ -246,7 +246,35 @@ var levelOrder = function(root) {
 
 ```
 
+TypeScript：
+
+```typescript
+function levelOrder(root: TreeNode | null): number[][] {
+    let helperQueue: TreeNode[] = [];
+    let res: number[][] = [];
+    let tempArr: number[] = [];
+    if (root !== null) helperQueue.push(root);
+    let curNode: TreeNode;
+    while (helperQueue.length > 0) {
+        for (let i = 0, length = helperQueue.length; i < length; i++) {
+            curNode = helperQueue.shift()!;
+            tempArr.push(curNode.val);
+            if (curNode.left !== null) {
+                helperQueue.push(curNode.left);
+            }
+            if (curNode.right !== null) {
+                helperQueue.push(curNode.right);
+            }
+        }
+        res.push(tempArr);
+        tempArr = [];
+    }
+    return res;
+};
+```
+
 Swift:
+
 ```swift
 func levelOrder(_ root: TreeNode?) -> [[Int]] {
     var res = [[Int]]()
@@ -454,7 +482,31 @@ var levelOrderBottom = function(root) {
 };
 ```
 
+TypeScript:
+
+```typescript
+function levelOrderBottom(root: TreeNode | null): number[][] {
+    let helperQueue: TreeNode[] = [];
+    let resArr: number[][] = [];
+    let tempArr: number[] = [];
+    let tempNode: TreeNode;
+    if (root !== null) helperQueue.push(root);
+    while (helperQueue.length > 0) {
+        for (let i = 0, length = helperQueue.length; i < length; i++) {
+            tempNode = helperQueue.shift()!;
+            tempArr.push(tempNode.val);
+            if (tempNode.left !== null) helperQueue.push(tempNode.left);
+            if (tempNode.right !== null) helperQueue.push(tempNode.right);
+        }
+        resArr.push(tempArr);
+        tempArr = [];
+    }
+    return resArr.reverse();
+};
+```
+
 Swift:
+
 ```swift
 func levelOrderBottom(_ root: TreeNode?) -> [[Int]] {
     var res =  [[Int]]()
@@ -657,7 +709,28 @@ var rightSideView = function(root) {
 };
 ```
 
+TypeScript：
+
+```typescript
+function rightSideView(root: TreeNode | null): number[] {
+    let helperQueue: TreeNode[] = [];
+    let resArr: number[] = [];
+    let tempNode: TreeNode;
+    if (root !== null) helperQueue.push(root);
+    while (helperQueue.length > 0) {
+        for (let i = 0, length = helperQueue.length; i < length; i++) {
+            tempNode = helperQueue.shift()!;
+            if (i === length - 1) resArr.push(tempNode.val);
+            if (tempNode.left !== null) helperQueue.push(tempNode.left);
+            if (tempNode.right !== null) helperQueue.push(tempNode.right);
+        }
+    }
+    return resArr;
+};
+```
+
 Swift:
+
 ```swift
 func rightSideView(_ root: TreeNode?) -> [Int] {
     var res = [Int]()
@@ -868,7 +941,32 @@ var averageOfLevels = function(root) {
 };
 ```
 
+TypeScript：
+
+```typescript
+function averageOfLevels(root: TreeNode | null): number[] {
+    let helperQueue: TreeNode[] = [];
+    let resArr: number[] = [];
+    let total: number = 0;
+    let tempNode: TreeNode;
+    if (root !== null) helperQueue.push(root);
+    while (helperQueue.length > 0) {
+        let length = helperQueue.length;
+        for (let i = 0; i < length; i++) {
+            tempNode = helperQueue.shift()!;
+            total += tempNode.val;
+            if (tempNode.left) helperQueue.push(tempNode.left);
+            if (tempNode.right) helperQueue.push(tempNode.right);
+        }
+        resArr.push(total / length);
+        total = 0;
+    }
+    return resArr;
+};
+```
+
 Swift:
+
 ```swift
 func averageOfLevels(_ root: TreeNode?) -> [Double] {
     var res = [Double]()
@@ -1092,7 +1190,30 @@ var levelOrder = function(root) {
 };
 ```
 
+TypeScript:
+
+```typescript
+function levelOrder(root: Node | null): number[][] {
+    let helperQueue: Node[] = [];
+    let resArr: number[][] = [];
+    let tempArr: number[] = [];
+    if (root !== null) helperQueue.push(root);
+    let curNode: Node;
+    while (helperQueue.length > 0) {
+        for (let i = 0, length = helperQueue.length; i < length; i++) {
+            curNode = helperQueue.shift()!;
+            tempArr.push(curNode.val);
+            helperQueue.push(...curNode.children);
+        }
+        resArr.push(tempArr);
+        tempArr = [];
+    }
+    return resArr;
+};
+```
+
 Swift:
+
 ```swift
 func levelOrder(_ root: Node?) -> [[Int]] {
     var res = [[Int]]()
@@ -1272,7 +1393,34 @@ var largestValues = function(root) {
 };
 ```
 
+TypeScript:
+
+```typescript
+function largestValues(root: TreeNode | null): number[] {
+    let helperQueue: TreeNode[] = [];
+    let resArr: number[] = [];
+    let tempNode: TreeNode;
+    let max: number = 0;
+    if (root !== null) helperQueue.push(root);
+    while (helperQueue.length > 0) {
+        for (let i = 0, length = helperQueue.length; i < length; i++) {
+            tempNode = helperQueue.shift()!;
+            if (i === 0) {
+                max = tempNode.val;
+            } else {
+                max = max > tempNode.val ? max : tempNode.val;
+            }
+            if (tempNode.left) helperQueue.push(tempNode.left);
+            if (tempNode.right) helperQueue.push(tempNode.right);
+        }
+        resArr.push(max);
+    }
+    return resArr;
+};
+```
+
 Swift:
+
 ```swift
 func largestValues(_ root: TreeNode?) -> [Int] {
     var res = [Int]()
@@ -1463,6 +1611,31 @@ var connect = function(root) {
 };
 
 ```
+TypeScript:
+
+```typescript
+function connect(root: Node | null): Node | null {
+    let helperQueue: Node[] = [];
+    let preNode: Node, curNode: Node;
+    if (root !== null) helperQueue.push(root);
+    while (helperQueue.length > 0) {
+        for (let i = 0, length = helperQueue.length; i < length; i++) {
+            if (i === 0) {
+                preNode = helperQueue.shift()!;
+            } else {
+                curNode = helperQueue.shift()!;
+                preNode.next = curNode;
+                preNode = curNode;
+            }
+            if (preNode.left) helperQueue.push(preNode.left);
+            if (preNode.right) helperQueue.push(preNode.right);
+        }
+        preNode.next = null;
+    }
+    return root;
+};
+```
+
 go:
 
 ```GO
@@ -1689,6 +1862,31 @@ var connect = function(root) {
     return root;
 };
 ```
+TypeScript:
+
+```typescript
+function connect(root: Node | null): Node | null {
+    let helperQueue: Node[] = [];
+    let preNode: Node, curNode: Node;
+    if (root !== null) helperQueue.push(root);
+    while (helperQueue.length > 0) {
+        for (let i = 0, length = helperQueue.length; i < length; i++) {
+            if (i === 0) {
+                preNode = helperQueue.shift()!;
+            } else {
+                curNode = helperQueue.shift()!;
+                preNode.next = curNode;
+                preNode = curNode;
+            }
+            if (preNode.left) helperQueue.push(preNode.left);
+            if (preNode.right) helperQueue.push(preNode.right);
+        }
+        preNode.next = null;
+    }
+    return root;
+};
+```
+
 go:
 
 ```GO
@@ -1933,7 +2131,28 @@ var maxDepth = function(root) {
 };
 ```
 
+TypeScript:
+
+```typescript
+function maxDepth(root: TreeNode | null): number {
+    let helperQueue: TreeNode[] = [];
+    let resDepth: number = 0;
+    let tempNode: TreeNode;
+    if (root !== null) helperQueue.push(root);
+    while (helperQueue.length > 0) {
+        resDepth++;
+        for (let i = 0, length = helperQueue.length; i < length; i++) {
+            tempNode = helperQueue.shift()!;
+            if (tempNode.left) helperQueue.push(tempNode.left);
+            if (tempNode.right) helperQueue.push(tempNode.right);
+        }
+    }
+    return resDepth;
+};
+```
+
 Swift:
+
 ```swift
 func maxDepth(_ root: TreeNode?) -> Int {
     guard let root = root else {
@@ -2130,7 +2349,29 @@ var minDepth = function(root) {
 };
 ```
 
+TypeScript:
+
+```typescript
+function minDepth(root: TreeNode | null): number {
+    let helperQueue: TreeNode[] = [];
+    let resMin: number = 0;
+    let tempNode: TreeNode;
+    if (root !== null) helperQueue.push(root);
+    while (helperQueue.length > 0) {
+        resMin++;
+        for (let i = 0, length = helperQueue.length; i < length; i++) {
+            tempNode = helperQueue.shift()!;
+            if (tempNode.left === null && tempNode.right === null) return resMin;
+            if (tempNode.left !== null) helperQueue.push(tempNode.left);
+            if (tempNode.right !== null) helperQueue.push(tempNode.right);
+        }
+    }
+    return resMin;
+};
+```
+
 Swift：
+
 ```swift
 func minDepth(_ root: TreeNode?) -> Int {
     guard let root = root else {

problems/0112.路径总和.md

@@ -531,82 +531,63 @@ class solution:
 ```go
 //递归法
 /**
- * definition for a binary tree node.
+ * Definition for a binary tree node.
- * type treenode struct {
+ * type TreeNode struct {
- *     val int
+ *     Val int
- *     left *treenode
+ *     Left *TreeNode
- *     right *treenode
+ *     Right *TreeNode
  * }
  */
-func haspathsum(root *treenode, targetsum int) bool {
+func hasPathSum(root *TreeNode, targetSum int) bool {
-    var flage bool //找没找到的标志
+    if root == nil {
-    if root==nil{
+        return false
-        return flage
     }
-    pathsum(root,0,targetsum,&flage)
+    
-    return flage
+    targetSum -= root.Val // 将targetSum在遍历每层的时候都减去本层节点的值
-}
+    if root.Left == nil && root.Right == nil && targetSum == 0 { // 如果剩余的targetSum为0, 则正好就是符合的结果
-func pathsum(root *treenode, sum int,targetsum int,flage *bool){
+        return true
-    sum+=root.val
-    if root.left==nil&&root.right==nil&&sum==targetsum{
-        *flage=true
-        return
-    }
-    if root.left!=nil&&!(*flage){//左节点不为空且还没找到
-        pathsum(root.left,sum,targetsum,flage)
-    } 
-    if root.right!=nil&&!(*flage){//右节点不为空且没找到
-        pathsum(root.right,sum,targetsum,flage)
     }
+    return hasPathSum(root.Left, targetSum) || hasPathSum(root.Right, targetSum) // 否则递归找
 }
 ```
 
-113 递归法
+113. 路径总和 II
 
 ```go
 /**
- * definition for a binary tree node.
+ * Definition for a binary tree node.
- * type treenode struct {
+ * type TreeNode struct {
- *     val int
+ *     Val int
- *     left *treenode
+ *     Left *TreeNode
- *     right *treenode
+ *     Right *TreeNode
  * }
  */
-func pathsum(root *treenode, targetsum int) [][]int {
+func pathSum(root *TreeNode, targetSum int) [][]int {
-    var result [][]int//最终结果
+    result := make([][]int, 0)
-    if root==nil{
+    traverse(root, &result, new([]int), targetSum)
-        return result
-    }
-    var sumnodes []int//经过路径的节点集合
-    haspathsum(root,&sumnodes,targetsum,&result)
     return result
 }
-func haspathsum(root *treenode,sumnodes *[]int,targetsum int,result *[][]int){
+
-    *sumnodes=append(*sumnodes,root.val)
+func traverse(node *TreeNode, result *[][]int, currPath *[]int, targetSum int) {
-    if root.left==nil&&root.right==nil{//叶子节点
+    if node == nil { // 这个判空也可以挪到递归遍历左右子树时去判断
-        fmt.println(*sumnodes)
+        return
-        var sum int
-        var number int
-        for k,v:=range *sumnodes{//求该路径节点的和
-            sum+=v
-            number=k
     }
-        tempnodes:=make([]int,number+1)//新的nodes接受指针里的值，防止最终指针里的值发生变动，导致最后的结果都是最后一个sumnodes的值
+
-        for k,v:=range *sumnodes{
+    targetSum -= node.Val // 将targetSum在遍历每层的时候都减去本层节点的值
-            tempnodes[k]=v
+    *currPath = append(*currPath, node.Val) // 把当前节点放到路径记录里
+    
+    if node.Left == nil && node.Right == nil && targetSum == 0 { // 如果剩余的targetSum为0, 则正好就是符合的结果
+        // 不能直接将currPath放到result里面, 因为currPath是共享的, 每次遍历子树时都会被修改
+        pathCopy := make([]int, len(*currPath)) 
+        for i, element := range *currPath {
+            pathCopy[i] = element
         }
-        if sum==targetsum{
+        *result = append(*result, pathCopy) // 将副本放到结果集里
-            *result=append(*result,tempnodes)
-        }
-    }
-    if root.left!=nil{
-        haspathsum(root.left,sumnodes,targetsum,result)
-        *sumnodes=(*sumnodes)[:len(*sumnodes)-1]//回溯
-    }
-    if root.right!=nil{
-        haspathsum(root.right,sumnodes,targetsum,result)
-        *sumnodes=(*sumnodes)[:len(*sumnodes)-1]//回溯
     }
+
+    traverse(node.Left, result, currPath, targetSum)
+    traverse(node.Right, result, currPath, targetSum)
+    *currPath = (*currPath)[:len(*currPath)-1] // 当前节点遍历完成, 从路径记录里删除掉
 }
 ```
 

problems/0416.分割等和子集.md

@@ -210,6 +210,45 @@ class Solution {
 }
 ```
 
+二维数组版本（易于理解）：
+```Java
+class Solution {
+    public boolean canPartition(int[] nums) {
+        int sum = 0;
+        for (int i = 0; i < nums.length; i++) {
+            sum += nums[i];
+        }
+
+        if (sum % 2 == 1)
+            return false;
+        int target = sum / 2;
+
+        //dp[i][j]代表可装物品为0-i，背包容量为j的情况下，背包内容量的最大价值
+        int[][] dp = new int[nums.length][target + 1];
+
+        //初始化,dp[0][j]的最大价值nums[0](if j > weight[i])
+        //dp[i][0]均为0，不用初始化
+        for (int j = nums[0]; j <= target; j++) {
+            dp[0][j] = nums[0];
+        }
+
+        //遍历物品，遍历背包
+        //递推公式:
+        for (int i = 1; i < nums.length; i++) {
+            for (int j = 0; j <= target; j++) {
+                //背包容量可以容纳nums[i]
+                if (j >= nums[i]) {
+                    dp[i][j] = Math.max(dp[i - 1][j], dp[i - 1][j - nums[i]] + nums[i]);
+                } else {
+                    dp[i][j] = dp[i - 1][j];
+                }
+            }
+        }
+
+        return dp[nums.length - 1][target] == target;
+    }
+}
+```
 Python：
 ```python
 class Solution:

problems/1049.最后一块石头的重量II.md

@@ -153,6 +153,8 @@ public:
 
 
 Java：
+
+一维数组版本
 ```Java
 class Solution {
     public int lastStoneWeightII(int[] stones) {
@@ -173,6 +175,41 @@ class Solution {
         return sum - 2 * dp[target];
     }
 }
+```
+二维数组版本（便于理解）
+```Java
+class Solution {
+    public int lastStoneWeightII(int[] stones) {
+        int sum = 0;
+        for (int s : stones) {
+            sum += s;
+        }
+
+        int target = sum / 2;
+        //初始化，dp[i][j]为可以放0-i物品，背包容量为j的情况下背包中的最大价值
+        int[][] dp = new int[stones.length][target + 1];
+        //dp[i][0]默认初始化为0
+        //dp[0][j]取决于stones[0]
+        for (int j = stones[0]; j <= target; j++) {
+            dp[0][j] = stones[0];
+        }
+
+        for (int i = 1; i < stones.length; i++) {
+            for (int j = 1; j <= target; j++) {//注意是等于
+                if (j >= stones[i]) {
+                    //不放:dp[i - 1][j] 放:dp[i - 1][j - stones[i]] + stones[i]
+                    dp[i][j] = Math.max(dp[i - 1][j], dp[i - 1][j - stones[i]] + stones[i]);
+                } else {
+                    dp[i][j] = dp[i - 1][j];
+                }
+            }
+        }
+
+        System.out.println(dp[stones.length - 1][target]);
+        return (sum - dp[stones.length - 1][target]) - dp[stones.length - 1][target];
+    }
+}
+
 ```
 
 Python：

problems/二叉树的统一迭代法.md

@@ -522,7 +522,75 @@ var postorderTraversal = function(root, res = []) {
 
 ```
 
+TypeScript：
 
+```typescript
+// 前序遍历（迭代法）
+function preorderTraversal(root: TreeNode | null): number[] {
+    let helperStack: (TreeNode | null)[] = [];
+    let res: number[] = [];
+    let curNode: TreeNode | null;
+    if (root === null) return res;
+    helperStack.push(root);
+    while (helperStack.length > 0) {
+        curNode = helperStack.pop()!;
+        if (curNode !== null) {
+            if (curNode.right !== null) helperStack.push(curNode.right);
+            helperStack.push(curNode);
+            helperStack.push(null);
+            if (curNode.left !== null) helperStack.push(curNode.left);
+        } else {
+            curNode = helperStack.pop()!;
+            res.push(curNode.val);
+        }
+    }
+    return res;
+};
+
+// 中序遍历（迭代法）
+function inorderTraversal(root: TreeNode | null): number[] {
+    let helperStack: (TreeNode | null)[] = [];
+    let res: number[] = [];
+    let curNode: TreeNode | null;
+    if (root === null) return res;
+    helperStack.push(root);
+    while (helperStack.length > 0) {
+        curNode = helperStack.pop()!;
+        if (curNode !== null) {
+            if (curNode.right !== null) helperStack.push(curNode.right);
+            helperStack.push(curNode);
+            helperStack.push(null);
+            if (curNode.left !== null) helperStack.push(curNode.left);
+        } else {
+            curNode = helperStack.pop()!;
+            res.push(curNode.val);
+        }
+    }
+    return res;
+};
+
+// 后序遍历（迭代法）
+function postorderTraversal(root: TreeNode | null): number[] {
+    let helperStack: (TreeNode | null)[] = [];
+    let res: number[] = [];
+    let curNode: TreeNode | null;
+    if (root === null) return res;
+    helperStack.push(root);
+    while (helperStack.length > 0) {
+        curNode = helperStack.pop()!;
+        if (curNode !== null) {
+            if (curNode.right !== null) helperStack.push(curNode.right);
+            helperStack.push(curNode);
+            helperStack.push(null);
+            if (curNode.left !== null) helperStack.push(curNode.left);
+        } else {
+            curNode = helperStack.pop()!;
+            res.push(curNode.val);
+        }
+    }
+    return res;
+};
+```
 
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 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>