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Commit a530ae4

Browse files
Merge branch 'youngyangyang04:master' into master
2 parents 30526c1 + 312e7d8 commit a530ae4

7 files changed

+343
-2
lines changed

‎problems/0112.路径总和.md

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Original file line numberDiff line numberDiff line change
@@ -486,6 +486,92 @@ class Solution:
486486

487487
Go:
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> 112. 路径总和
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```go
492+
//递归法
493+
/**
494+
* Definition for a binary tree node.
495+
* type TreeNode struct {
496+
* Val int
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* Left *TreeNode
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* Right *TreeNode
499+
* }
500+
*/
501+
func hasPathSum(root *TreeNode, targetSum int) bool {
502+
var flage bool //找没找到的标志
503+
if root==nil{
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return flage
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}
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pathSum(root,0,targetSum,&flage)
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return flage
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}
509+
func pathSum(root *TreeNode, sum int,targetSum int,flage *bool){
510+
sum+=root.Val
511+
if root.Left==nil&&root.Right==nil&&sum==targetSum{
512+
*flage=true
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return
514+
}
515+
if root.Left!=nil&&!(*flage){//左节点不为空且还没找到
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pathSum(root.Left,sum,targetSum,flage)
517+
}
518+
if root.Right!=nil&&!(*flage){//右节点不为空且没找到
519+
pathSum(root.Right,sum,targetSum,flage)
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}
521+
}
522+
```
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> 113 递归法
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```go
529+
/**
530+
* Definition for a binary tree node.
531+
* type TreeNode struct {
532+
* Val int
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* Left *TreeNode
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* Right *TreeNode
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* }
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*/
537+
func pathSum(root *TreeNode, targetSum int) [][]int {
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var result [][]int//最终结果
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if root==nil{
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return result
541+
}
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var sumNodes []int//经过路径的节点集合
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hasPathSum(root,&sumNodes,targetSum,&result)
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return result
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}
546+
func hasPathSum(root *TreeNode,sumNodes *[]int,targetSum int,result *[][]int){
547+
*sumNodes=append(*sumNodes,root.Val)
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if root.Left==nil&&root.Right==nil{//叶子节点
549+
fmt.Println(*sumNodes)
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var sum int
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var number int
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for k,v:=range *sumNodes{//求该路径节点的和
553+
sum+=v
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number=k
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}
556+
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
557+
for k,v:=range *sumNodes{
558+
tempNodes[k]=v
559+
}
560+
if sum==targetSum{
561+
*result=append(*result,tempNodes)
562+
}
563+
}
564+
if root.Left!=nil{
565+
hasPathSum(root.Left,sumNodes,targetSum,result)
566+
*sumNodes=(*sumNodes)[:len(*sumNodes)-1]//回溯
567+
}
568+
if root.Right!=nil{
569+
hasPathSum(root.Right,sumNodes,targetSum,result)
570+
*sumNodes=(*sumNodes)[:len(*sumNodes)-1]//回溯
571+
}
572+
}
573+
```
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489575
JavaScript:
490576

491577
0112.路径总和

‎problems/0239.滑动窗口最大值.md

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Original file line numberDiff line numberDiff line change
@@ -332,6 +332,66 @@ func maxSlidingWindow(nums []int, k int) []int {
332332

333333
```
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```go
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// 封装单调队列的方式解题
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type MyQueue struct {
338+
queue []int
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}
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func NewMyQueue() *MyQueue {
342+
return &MyQueue{
343+
queue: make([]int, 0),
344+
}
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}
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func (m *MyQueue) Front() int {
348+
return m.queue[0]
349+
}
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func (m *MyQueue) Back() int {
352+
return m.queue[len(m.queue)-1]
353+
}
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func (m *MyQueue) Empty() bool {
356+
return len(m.queue) == 0
357+
}
358+
359+
func (m *MyQueue) Push(val int) {
360+
for !m.Empty() && val > m.Back() {
361+
m.queue = m.queue[:len(m.queue)-1]
362+
}
363+
m.queue = append(m.queue, val)
364+
}
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func (m *MyQueue) Pop(val int) {
367+
if !m.Empty() && val == m.Front() {
368+
m.queue = m.queue[1:]
369+
}
370+
}
371+
372+
func maxSlidingWindow(nums []int, k int) []int {
373+
queue := NewMyQueue()
374+
length := len(nums)
375+
res := make([]int, 0)
376+
// 先将前k个元素放入队列
377+
for i := 0; i < k; i++ {
378+
queue.Push(nums[i])
379+
}
380+
// 记录前k个元素的最大值
381+
res = append(res, queue.Front())
382+
383+
for i := k; i < length; i++ {
384+
// 滑动窗口移除最前面的元素
385+
queue.Pop(nums[i-k])
386+
// 滑动窗口添加最后面的元素
387+
queue.Push(nums[i])
388+
// 记录最大值
389+
res = append(res, queue.Front())
390+
}
391+
return res
392+
}
393+
```
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335395
Javascript:
336396
```javascript
337397
var maxSlidingWindow = function (nums, k) {

‎problems/0242.有效的字母异位词.md

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Original file line numberDiff line numberDiff line change
@@ -130,7 +130,27 @@ class Solution:
130130
return True
131131
```
132132

133+
Python写法二(没有使用数组作为哈希表,只是介绍defaultdict这样一种解题思路):
134+
135+
```python
136+
class Solution:
137+
def isAnagram(self, s: str, t: str) -> bool:
138+
from collections import defaultdict
139+
140+
s_dict = defaultdict(int)
141+
t_dict = defaultdict(int)
142+
143+
for x in s:
144+
s_dict[x] += 1
145+
146+
for x in t:
147+
t_dict[x] += 1
148+
149+
return s_dict == t_dict
150+
```
151+
133152
Go:
153+
134154
```go
135155
func isAnagram(s string, t string) bool {
136156
if len(s)!=len(t){

‎problems/0343.整数拆分.md

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@@ -218,7 +218,7 @@ class Solution:
218218
# 假设对正整数 i 拆分出的第一个正整数是 j(1 <= j < i),则有以下两种方案:
219219
# 1) 将 i 拆分成 j 和 i−j 的和,且 i−j 不再拆分成多个正整数,此时的乘积是 j * (i-j)
220220
# 2) 将 i 拆分成 j 和 i−j 的和,且 i−j 继续拆分成多个正整数,此时的乘积是 j * dp[i-j]
221-
for j in range(1, i):
221+
for j in range(1, i-1):
222222
dp[i] = max(dp[i], max(j * (i - j), j * dp[i - j]))
223223
return dp[n]
224224
```

‎problems/0404.左叶子之和.md

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Original file line numberDiff line numberDiff line change
@@ -226,6 +226,71 @@ class Solution:
226226
```
227227
Go:
228228

229+
> 递归法
230+
231+
```go
232+
/**
233+
* Definition for a binary tree node.
234+
* type TreeNode struct {
235+
* Val int
236+
* Left *TreeNode
237+
* Right *TreeNode
238+
* }
239+
*/
240+
func sumOfLeftLeaves(root *TreeNode) int {
241+
var res int
242+
findLeft(root,&res)
243+
return res
244+
}
245+
func findLeft(root *TreeNode,res *int){
246+
//左节点
247+
if root.Left!=nil&&root.Left.Left==nil&&root.Left.Right==nil{
248+
*res=*res+root.Left.Val
249+
}
250+
if root.Left!=nil{
251+
findLeft(root.Left,res)
252+
}
253+
if root.Right!=nil{
254+
findLeft(root.Right,res)
255+
}
256+
}
257+
```
258+
259+
> 迭代法
260+
261+
```go
262+
/**
263+
* Definition for a binary tree node.
264+
* type TreeNode struct {
265+
* Val int
266+
* Left *TreeNode
267+
* Right *TreeNode
268+
* }
269+
*/
270+
func sumOfLeftLeaves(root *TreeNode) int {
271+
var res int
272+
queue:=list.New()
273+
queue.PushBack(root)
274+
for queue.Len()>0{
275+
length:=queue.Len()
276+
for i:=0;i<length;i++{
277+
node:=queue.Remove(queue.Front()).(*TreeNode)
278+
if node.Left!=nil&&node.Left.Left==nil&&node.Left.Right==nil{
279+
res=res+node.Left.Val
280+
}
281+
if node.Left!=nil{
282+
queue.PushBack(node.Left)
283+
}
284+
if node.Right!=nil{
285+
queue.PushBack(node.Right)
286+
}
287+
}
288+
}
289+
return res
290+
}
291+
```
292+
293+
229294
JavaScript:
230295
递归版本
231296
```javascript
@@ -275,6 +340,7 @@ var sumOfLeftLeaves = function(root) {
275340

276341

277342

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278344
-----------------------
279345
* 作者微信:[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
280346
* B站视频:[代码随想录](https://space.bilibili.com/525438321)

‎problems/0513.找树左下角的值.md

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Original file line numberDiff line numberDiff line change
@@ -298,6 +298,80 @@ class Solution:
298298
```
299299
Go:
300300

301+
> 递归法
302+
303+
```go
304+
/**
305+
* Definition for a binary tree node.
306+
* type TreeNode struct {
307+
* Val int
308+
* Left *TreeNode
309+
* Right *TreeNode
310+
* }
311+
*/
312+
var maxDeep int // 全局变量 深度
313+
var value int //全局变量 最终值
314+
func findBottomLeftValue(root *TreeNode) int {
315+
if root.Left==nil&&root.Right==nil{//需要提前判断一下(不要这个if的话提交结果会出错,但执行代码不会。防止这种情况出现,故先判断是否只有一个节点)
316+
return root.Val
317+
}
318+
findLeftValue (root,maxDeep)
319+
return value
320+
}
321+
func findLeftValue (root *TreeNode,deep int){
322+
//最左边的值在左边
323+
if root.Left==nil&&root.Right==nil{
324+
if deep>maxDeep{
325+
value=root.Val
326+
maxDeep=deep
327+
}
328+
}
329+
//递归
330+
if root.Left!=nil{
331+
deep++
332+
findLeftValue(root.Left,deep)
333+
deep--//回溯
334+
}
335+
if root.Right!=nil{
336+
deep++
337+
findLeftValue(root.Right,deep)
338+
deep--//回溯
339+
}
340+
}
341+
```
342+
343+
> 迭代法
344+
345+
```go
346+
/**
347+
* Definition for a binary tree node.
348+
* type TreeNode struct {
349+
* Val int
350+
* Left *TreeNode
351+
* Right *TreeNode
352+
* }
353+
*/
354+
func findBottomLeftValue(root *TreeNode) int {
355+
queue:=list.New()
356+
var gradation int
357+
queue.PushBack(root)
358+
for queue.Len()>0{
359+
length:=queue.Len()
360+
for i:=0;i<length;i++{
361+
node:=queue.Remove(queue.Front()).(*TreeNode)
362+
if i==0{gradation=node.Val}
363+
if node.Left!=nil{
364+
queue.PushBack(node.Left)
365+
}
366+
if node.Right!=nil{
367+
queue.PushBack(node.Right)
368+
}
369+
}
370+
}
371+
return gradation
372+
}
373+
```
374+
301375
JavaScript:
302376
1. 递归版本
303377
```javascript

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