Merge branch 'youngyangyang04:master' into master

Author: minghaha

problems/0198.打家劫舍.md

@@ -131,7 +131,20 @@ class Solution {
 ```
 
 Python：
-
+```python
+class Solution:
+    def rob(self, nums: List[int]) -> int:
+        if len(nums) == 0:
+            return 0
+        if len(nums) == 1:
+            return nums[0]
+        dp = [0] * len(nums)
+        dp[0] = nums[0]
+        dp[1] = max(nums[0], nums[1])
+        for i in range(2, len(nums)):
+            dp[i] = max(dp[i-2]+nums[i], dp[i-1])
+        return dp[-1]
+```
 
 Go：
 ```Go

problems/0222.完全二叉树的节点个数.md

@@ -308,6 +308,35 @@ class Solution:
 
 Go：
 
+递归版本
+
+```go
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+//本题直接就是求有多少个节点，无脑存进数组算长度就行了。
+func countNodes(root *TreeNode) int {
+    if root == nil {
+        return 0
+    }
+    res := 1
+    if root.Right != nil {
+        res += countNodes(root.Right)
+    }
+    if root.Left != nil {
+        res += countNodes(root.Left)
+    }
+    return res
+}
+```
+
+
+
 JavaScript:
 
 递归版本

problems/0337.打家劫舍III.md

@@ -287,6 +287,25 @@ class Solution {
 
 Python：
 
+> 动态规划
+```python
+class Solution:
+    def rob(self, root: TreeNode) -> int:
+        result = self.robTree(root)
+        return max(result[0], result[1])
+    
+    #长度为2的数组，0：不偷，1：偷
+    def robTree(self, cur):
+        if not cur:
+            return (0, 0) #这里返回tuple, 也可以返回list
+        left = self.robTree(cur.left)
+        right = self.robTree(cur.right)
+        #偷cur
+        val1 = cur.val + left[0] + right[0]
+        #不偷cur
+        val2 = max(left[0], left[1]) + max(right[0], right[1])
+        return (val2, val1)
+```
 
 Go：
 

problems/0474.一和零.md

@@ -206,7 +206,43 @@ class Solution:
 ```
 
 Go：
+```go
+func findMaxForm(strs []string, m int, n int) int {
+	// 定义数组
+	dp := make([][]int, m+1)
+	for i,_ := range dp {
+		dp[i] = make([]int, n+1 )
+	}
+	// 遍历
+	for i:=0;i<len(strs);i++ {
+		zeroNum,oneNum := 0 , 0
+		//计算0,1 个数
+		//或者直接strings.Count(strs[i],"0")
+		for _,v := range strs[i] {
+			if v == '0' {
+				zeroNum++
+			}
+		}
+		oneNum = len(strs[i])-zeroNum
+		// 从后往前 遍历背包容量
+		for j:= m ; j >= zeroNum;j-- {
+			for k:=n ; k >= oneNum;k-- {
+				// 推导公式
+				dp[j][k] = max(dp[j][k],dp[j-zeroNum][k-oneNum]+1)
+			}
+		}
+		//fmt.Println(dp)
+	}
+	return dp[m][n]
+}
 
+func max(a,b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
+```
 
 
 

problems/0530.二叉搜索树的最小绝对差.md

@@ -151,7 +151,30 @@ public:
 
 
 Java：
-
+递归
+```java
+class Solution {
+    TreeNode pre;// 记录上一个遍历的结点
+    int result = Integer.MAX_VALUE;
+    public int getMinimumDifference(TreeNode root) {
+       if(root==null)return 0;
+       traversal(root);
+       return result;
+    }
+    public void traversal(TreeNode root){
+        if(root==null)return;
+        //左
+        traversal(root.left);
+        //中
+        if(pre!=null){
+            result = Math.min(result,root.val-pre.val);
+        }
+        pre = root;
+        //右
+        traversal(root.right);
+    }
+}
+```
 ```Java
 class Solution {
     TreeNode pre;// 记录上一个遍历的结点

problems/二叉树中递归带着回溯.md

@@ -257,6 +257,83 @@ Java：
 
 Python：
 
+100.相同的树
+> 递归法
+```python
+class Solution:
+    def isSameTree(self, p: TreeNode, q: TreeNode) -> bool:
+        return self.compare(p, q)
+        
+    def compare(self, tree1, tree2):
+        if not tree1 and tree2:
+            return False
+        elif tree1 and not tree2:
+            return False
+        elif not tree1 and not tree2:
+            return True
+        elif tree1.val != tree2.val: #注意这里我没有使用else
+            return False
+        
+        #此时就是：左右节点都不为空，且数值相同的情况
+        #此时才做递归，做下一层的判断
+        compareLeft = self.compare(tree1.left, tree2.left) #左子树：左、 右子树：左
+        compareRight = self.compare(tree1.right, tree2.right) #左子树：右、 右子树：右
+        isSame = compareLeft and compareRight #左子树：中、 右子树：中（逻辑处理）
+        return isSame
+```
+
+257.二叉的所有路径
+> 递归中隐藏着回溯
+```python
+class Solution:
+    def binaryTreePaths(self, root: TreeNode) -> List[str]:
+        result = []
+        path = []
+        if not root:
+            return result
+        self.traversal(root, path, result)
+        return result
+        
+    def traversal(self, cur, path, result):
+        path.append(cur.val)
+        #这才到了叶子节点
+        if not cur.left and not cur.right:
+            sPath = ""
+            for i in range(len(path)-1):
+                sPath += str(path[i])
+                sPath += "->"
+            sPath += str(path[len(path)-1])
+            result.append(sPath)
+            return
+        if cur.left:
+            self.traversal(cur.left, path, result)
+            path.pop() #回溯
+        if cur.right:
+            self.traversal(cur.right, path, result)
+            path.pop() #回溯
+```
+
+> 精简版
+```python
+class Solution:
+    def binaryTreePaths(self, root: TreeNode) -> List[str]:
+        result = []
+        path = ""
+        if not root:
+            return result
+        self.traversal(root, path, result)
+        return result
+        
+    def traversal(self, cur, path, result):
+        path += str(cur.val) #中
+        if not cur.left and not cur.right:
+            result.append(path)
+            return
+        if cur.left:
+            self.traversal(cur.left, path+"->", result) #左  回溯就隐藏在这里
+        if cur.right:
+            self.traversal(cur.right, path+"->", result) #右 回溯就隐藏在这里
+```
 
 Go：
 

problems/背包理论基础01背包-1.md

@@ -273,7 +273,40 @@ Python：
 
 
 Go：
+```go
+func test_2_wei_bag_problem1(weight, value []int, bagWeight int) int {
+	// 定义dp数组
+	dp := make([][]int, len(weight))
+	for i, _ := range dp {
+		dp[i] = make([]int, bagWeight+1)
+	}
+	// 初始化
+	for j := bagWeight; j >= weight[0]; j-- {
+		dp[0][j] = dp[0][j-weight[0]] + value[0]
+	}
+	// 递推公式
+	for i := 1; i < len(weight); i++ {
+		//正序,也可以倒序
+		for  j := weight[i];j<= bagWeight ; j++ {
+			dp[i][j] = max(dp[i-1][j], dp[i-1][j-weight[i]]+value[i])
+		}		
+	}
+	return dp[len(weight)-1][bagWeight]
+}
+
+func max(a,b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
 
+func main() {
+	weight := []int{1,3,4}
+	value := []int{15,20,30}
+	test_2_wei_bag_problem1(weight,value,4)
+}
+```
 
 -----------------------
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)

problems/背包理论基础01背包-2.md

@@ -219,8 +219,37 @@ Python：
 
 
 Go：
+```go
+func test_1_wei_bag_problem(weight, value []int, bagWeight int) int {
+	// 定义 and 初始化
+	dp := make([]int,bagWeight+1)
+	// 递推顺序
+	for i := 0 ;i < len(weight) ; i++ {
+		// 这里必须倒序,区别二维,因为二维dp保存了i的状态
+		for j:= bagWeight; j >= weight[i] ; j-- {
+			// 递推公式
+			dp[j] = max(dp[j], dp[j-weight[i]]+value[i])
+		}
+	}
+	//fmt.Println(dp)
+	return dp[bagWeight]
+}
+
+func max(a,b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
 
 
+func main() {
+	weight := []int{1,3,4}
+	value := []int{15,20,30}
+	test_1_wei_bag_problem(weight,value,4)
+}
+```
+
 
 
 -----------------------