Merge branch 'youngyangyang04:master' into master

This commit is contained in:
fusunx
2021-05-17 19:06:43 -05:00
3 changed files with 94 additions and 3 deletions

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@ -348,8 +348,32 @@ class Solution {
```
Python
```python
// 递归法
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def hasPathSum(self, root: TreeNode, targetSum: int) -> bool:
def isornot(root,targetSum)->bool:
if (not root.left) and (not root.right) and targetSum == 0:return True // 遇到叶子节点并且计数为0
if (not root.left) and (not root.right):return False //遇到叶子节点计数不为0
if root.left:
targetSum -= root.left.val //只有左节点
if isornot(root.left,targetSum):return True //递归,处理节点
targetSum += root.left.val //回溯
if root.right:
targetSum -= root.right.val //只有右节点
if isornot(root.right,targetSum):return True //递归,处理右节点
targetSum += root.right.val //回溯
return False
if root == None:return False //别忘记处理空TreeNode
else:return isornot(root,targetSum-root.val)
```
Go
JavaScript

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@ -160,7 +160,28 @@ Python
Go
```Go
func findLength(A []int, B []int) int {
m, n := len(A), len(B)
res := 0
dp := make([][]int, m+1)
for i := 0; i <= m; i++ {
dp[i] = make([]int, n+1)
}
for i := 1; i <= m; i++ {
for j := 1; j <= n; j++ {
if A[i-1] == B[j-1] {
dp[i][j] = dp[i-1][j-1] + 1
}
if dp[i][j] > res {
res = dp[i][j]
}
}
}
return res
}
```

View File

@ -170,7 +170,53 @@ class Solution {
```
Python
```python3
# 前序遍历-递归-LC144_二叉树的前序遍历
class Solution:
def preorderTraversal(self, root: TreeNode) -> List[int]:
# 保存结果
result = []
def traversal(root: TreeNode):
if root == None:
return
result.append(root.val) # 前序
traversal(root.left) # 左
traversal(root.right) # 右
traversal(root)
return result
# 中序遍历-递归-LC94_二叉树的中序遍历
class Solution:
def inorderTraversal(self, root: TreeNode) -> List[int]:
result = []
def traversal(root: TreeNode):
if root == None:
return
traversal(root.left) # 左
result.append(root.val) # 中序
traversal(root.right) # 右
traversal(root)
return result
# 后序遍历-递归-LC145_二叉树的后序遍历
class Solution:
def postorderTraversal(self, root: TreeNode) -> List[int]:
result = []
def traversal(root: TreeNode):
if root == None:
return
traversal(root.left) # 左
traversal(root.right) # 右
result.append(root.val) # 后序
traversal(root)
return result
```
Go