From 4a33ef6a04bb13ace9ab8a7551fd783815a4e0f9 Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sat, 19 Jun 2021 11:33:02 +0800 Subject: [PATCH 1/9] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200669.=E4=BF=AE?= =?UTF-8?q?=E5=89=AA=E4=BA=8C=E5=8F=89=E6=90=9C=E7=B4=A2=E6=A0=91=20Golang?= =?UTF-8?q?=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0669.修剪二叉搜索树 Golang版本 --- problems/0669.修剪二叉搜索树.md | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/problems/0669.修剪二叉搜索树.md b/problems/0669.修剪二叉搜索树.md index 06d99b9d..2a88f195 100644 --- a/problems/0669.修剪二叉搜索树.md +++ b/problems/0669.修剪二叉搜索树.md @@ -286,7 +286,33 @@ class Solution: return root ``` Go： +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ +func trimBST(root *TreeNode, low int, high int) *TreeNode { + if root==nil{ + return nil + } + if root.Valhigh{//如果该节点的值大于最大值，则该节点更换为该节点的左节点值，继续遍历 + left:=trimBST(root.Left,low,high) + return left + } + root.Left=trimBST(root.Left,low,high) + root.Right=trimBST(root.Right,low,high) + return root +} +``` From ed14cefdb171abdf7a6b295d912617889910c746 Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sat, 19 Jun 2021 15:32:30 +0800 Subject: [PATCH 2/9] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200108.=E5=B0=86?= =?UTF-8?q?=E6=9C=89=E5=BA=8F=E6=95=B0=E7=BB=84=E8=BD=AC=E6=8D=A2=E4=B8=BA?= =?UTF-8?q?=E4=BA=8C=E5=8F=89=E6=90=9C=E7=B4=A2=E6=A0=91=20Golang=E7=89=88?= =?UTF-8?q?=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0108.将有序数组转换为二叉搜索树 Golang版本 --- ...将有序数组转换为二叉搜索树.md | 23 +++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/problems/0108.将有序数组转换为二叉搜索树.md b/problems/0108.将有序数组转换为二叉搜索树.md index 2692be47..35b8bb2e 100644 --- a/problems/0108.将有序数组转换为二叉搜索树.md +++ b/problems/0108.将有序数组转换为二叉搜索树.md @@ -258,6 +258,29 @@ class Solution: Go： +> 递归（隐含回溯） + +```go +/** + * Definition for a binary tree node. + * type TreeNode struct { + * Val int + * Left *TreeNode + * Right *TreeNode + * } + */ + //递归（隐含回溯） +func sortedArrayToBST(nums []int) *TreeNode { + if len(nums)==0{return nil}//终止条件，最后数组为空则可以返回 + root:=&TreeNode{nums[len(nums)/2],nil,nil}//按照BSL的特点，从中间构造节点 + root.Left=sortedArrayToBST(nums[:len(nums)/2])//数组的左边为左子树 + root.Right=sortedArrayToBST(nums[len(nums)/2+1:])//数字的右边为右子树 + return root +} +``` + + + ----------------------- From d2e05f9b047bfd92faab571fa8276a776ce34b2f Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sat, 19 Jun 2021 16:30:36 +0800 Subject: [PATCH 3/9] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200538.=E6=8A=8A?= =?UTF-8?q?=E4=BA=8C=E5=8F=89=E6=90=9C=E7=B4=A2=E6=A0=91=E8=BD=AC=E6=8D=A2?= =?UTF-8?q?=E4=B8=BA=E7=B4=AF=E5=8A=A0=E6=A0=91=20Golang=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0538.把二叉搜索树转换为累加树 Golang版本 --- ...38.把二叉搜索树转换为累加树.md | 20 +++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/problems/0538.把二叉搜索树转换为累加树.md b/problems/0538.把二叉搜索树转换为累加树.md index 765e78d3..06a53ce7 100644 --- a/problems/0538.把二叉搜索树转换为累加树.md +++ b/problems/0538.把二叉搜索树转换为累加树.md @@ -219,6 +219,26 @@ class Solution: Go： +> 弄一个sum暂存其和值 + +```go + //右中左 +func bstToGst(root *TreeNode) *TreeNode { + var sum int + RightMLeft(root,&sum) + return root +} +func RightMLeft(root *TreeNode,sum *int) *TreeNode { + if root==nil{return nil}//终止条件，遇到空节点就返回 + RightMLeft(root.Right,sum)//先遍历右边 + temp:=*sum//暂存总和值 + *sum+=root.Val//将总和值变更 + root.Val+=temp//更新节点值 + RightMLeft(root.Left,sum)//遍历左节点 + return root +} +``` + ----------------------- From 2e8ba2bbb8e27132129d83c64795ba8feaed39d2 Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sat, 19 Jun 2021 20:25:29 +0800 Subject: [PATCH 4/9] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200216.=E7=BB=84?= =?UTF-8?q?=E5=90=88=E6=80=BB=E5=92=8CIII=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0216.组合总和III go版本 --- problems/0216.组合总和III.md | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/problems/0216.组合总和III.md b/problems/0216.组合总和III.md index 9f75b23d..67e67ad0 100644 --- a/problems/0216.组合总和III.md +++ b/problems/0216.组合总和III.md @@ -284,6 +284,37 @@ class Solution: Go： + +> 回溯+减枝 + +```go +func combinationSum3(k int, n int) [][]int { + var track []int// 遍历路径 + var result [][]int// 存放结果集 + backTree(n,k,1,&track,&result) + return result +} +func backTree(n,k,startIndex int,track *[]int,result *[][]int){ + if len(*track)==k{ + var sum int + tmp:=make([]int,k) + for k,v:=range *track{ + sum+=v + tmp[k]=v + } + if sum==n{ + *result=append(*result,tmp) + } + return + } + for i:=startIndex;i<=9-(k-len(*track))+1;i++{//减枝（k-len(*track)表示还剩多少个可填充的元素） + *track=append(*track,i)//记录路径 + backTree(n,k,i+1,track,result)//递归 + *track=(*track)[:len(*track)-1]//回溯 + } +} +``` + javaScript: ```js From d73ef9071538e4f8660d1aa8d62fe815304cf8bf Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sat, 19 Jun 2021 21:35:01 +0800 Subject: [PATCH 5/9] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200017.=E7=94=B5?= =?UTF-8?q?=E8=AF=9D=E5=8F=B7=E7=A0=81=E7=9A=84=E5=AD=97=E6=AF=8D=E7=BB=84?= =?UTF-8?q?=E5=90=88=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0017.电话号码的字母组合 go版本 --- problems/0017.电话号码的字母组合.md | 40 ++++++++++++++++++++ 1 file changed, 40 insertions(+) diff --git a/problems/0017.电话号码的字母组合.md b/problems/0017.电话号码的字母组合.md index aefee698..1562052c 100644 --- a/problems/0017.电话号码的字母组合.md +++ b/problems/0017.电话号码的字母组合.md @@ -342,6 +342,46 @@ class Solution: Go： + +> 主要在于递归中传递下一个数字 + +```go +func letterCombinations(digits string) []string { + lenth:=len(digits) + if lenth==0 ||lenth>4{ + return nil + } + digitsMap:= [10]string{ + "", // 0 + "", // 1 + "abc", // 2 + "def", // 3 + "ghi", // 4 + "jkl", // 5 + "mno", // 6 + "pqrs", // 7 + "tuv", // 8 + "wxyz", // 9 + } + res:=make([]string,0) + recursion("",digits,0,digitsMap,&res) + return res +} +func recursion(tempString ,digits string, Index int,digitsMap [10]string, res *[]string) {//index表示第几个数字 + if len(tempString)==len(digits){//终止条件，字符串长度等于digits的长度 + *res=append(*res,tempString) + return + } + tmpK:=digits[Index]-'0' // 将index指向的数字转为int（确定下一个数字） + letter:=digitsMap[tmpK]// 取数字对应的字符集 + for i:=0;i Date: Sat, 19 Jun 2021 22:05:48 +0800 Subject: [PATCH 6/9] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200039.=E7=BB=84?= =?UTF-8?q?=E5=90=88=E6=80=BB=E5=92=8C=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0039.组合总和 go版本 --- problems/0039.组合总和.md | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/problems/0039.组合总和.md b/problems/0039.组合总和.md index e3e4a117..ba8128b5 100644 --- a/problems/0039.组合总和.md +++ b/problems/0039.组合总和.md @@ -286,6 +286,39 @@ class Solution: ``` Go： + +> 主要在于递归中传递下一个数字 + +```go +func combinationSum(candidates []int, target int) [][]int { + var trcak []int + var res [][]int + backtracking(0,0,target,candidates,trcak,&res) + return res +} +func backtracking(startIndex,sum,target int,candidates,trcak []int,res *[][]int){ + //终止条件 + if sum==target{ + tmp:=make([]int,len(trcak)) + copy(tmp,trcak)//拷贝 + *res=append(*res,tmp)//放入结果集 + return + } + if sum>target{return} + //回溯 + for i:=startIndex;i Date: Sat, 19 Jun 2021 23:23:34 +0800 Subject: [PATCH 7/9] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200040.=E7=BB=84?= =?UTF-8?q?=E5=90=88=E6=80=BB=E5=92=8CII=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0040.组合总和II go版本 --- problems/0040.组合总和II.md | 42 +++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/problems/0040.组合总和II.md b/problems/0040.组合总和II.md index a462b524..021bba94 100644 --- a/problems/0040.组合总和II.md +++ b/problems/0040.组合总和II.md @@ -314,6 +314,48 @@ class Solution: ``` Go： + +> 主要在于如何在回溯中去重 + +```go +func combinationSum2(candidates []int, target int) [][]int { + var trcak []int + var res [][]int + var history map[int]bool + history=make(map[int]bool) + sort.Ints(candidates) + backtracking(0,0,target,candidates,trcak,&res,history) + return res +} +func backtracking(startIndex,sum,target int,candidates,trcak []int,res *[][]int,history map[int]bool){ + //终止条件 + if sum==target{ + tmp:=make([]int,len(trcak)) + copy(tmp,trcak)//拷贝 + *res=append(*res,tmp)//放入结果集 + return + } + if sum>target{return} + //回溯 + // used[i - 1] == true，说明同一树支candidates[i - 1]使用过 + // used[i - 1] == false，说明同一树层candidates[i - 1]使用过 + for i:=startIndex;i0&&candidates[i]==candidates[i-1]&&history[i-1]==false{ + continue + } + //更新路径集合和sum + trcak=append(trcak,candidates[i]) + sum+=candidates[i] + history[i]=true + //递归 + backtracking(i+1,sum,target,candidates,trcak,res,history) + //回溯 + trcak=trcak[:len(trcak)-1] + sum-=candidates[i] + history[i]=false + } +} +``` javaScript： ```js From c430004a0b8b91419e43bb648b0b2c3b5a8b5db2 Mon Sep 17 00:00:00 2001 From: X-shuffle <53906918+X-shuffle@users.noreply.github.com> Date: Sun, 20 Jun 2021 14:47:48 +0800 Subject: [PATCH 8/9] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200131.=E5=88=86?= =?UTF-8?q?=E5=89=B2=E5=9B=9E=E6=96=87=E4=B8=B2=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0131.分割回文串 go版本 --- problems/0131.分割回文串.md | 44 ++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/problems/0131.分割回文串.md b/problems/0131.分割回文串.md index 9d23fd13..43453409 100644 --- a/problems/0131.分割回文串.md +++ b/problems/0131.分割回文串.md @@ -312,6 +312,50 @@ class Solution: ``` Go： +> 注意切片（go切片是披着值类型外衣的引用类型） + +```go +func partition(s string) [][]string { + var tmpString []string//切割字符串集合 + var res [][]string//结果集合 + backTracking(s,tmpString,0,&res) + return res +} +func backTracking(s string,tmpString []string,startIndex int,res *[][]string){ + if startIndex==len(s){//到达字符串末尾了 + //进行一次切片拷贝，怕之后的操作影响tmpString切片内的值 + t := make([]string, len(tmpString)) + copy(t, tmpString) + *res=append(*res,t) + } + for i:=startIndex;i Date: Sun, 20 Jun 2021 16:39:35 +0800 Subject: [PATCH 9/9] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200093.=E5=A4=8D?= =?UTF-8?q?=E5=8E=9FIP=E5=9C=B0=E5=9D=80=20go=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加 0093.复原IP地址 go版本 --- problems/0093.复原IP地址.md | 41 +++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/problems/0093.复原IP地址.md b/problems/0093.复原IP地址.md index a8b9a215..1c8e4069 100644 --- a/problems/0093.复原IP地址.md +++ b/problems/0093.复原IP地址.md @@ -367,6 +367,47 @@ var restoreIpAddresses = function(s) { } }; ``` +Go： +> 回溯（对于前导 0的IP（特别注意s[startIndex]=='0'的判断，不应该写成s[startIndex]==0，因为s截取出来不是数字）） + +```go +func restoreIpAddresses(s string) []string { + var res,path []string + backTracking(s,path,0,&res) + return res +} +func backTracking(s string,path []string,startIndex int,res *[]string){ + //终止条件 + if startIndex==len(s)&&len(path)==4{ + tmpIpString:=path[0]+"."+path[1]+"."+path[2]+"."+path[3] + *res=append(*res,tmpIpString) + } + for i:=startIndex;i1&&s[startIndex]=='0'{//对于前导 0的IP（特别注意s[startIndex]=='0'的判断，不应该写成s[startIndex]==0，因为s截取出来不是数字） + return false + } + if checkInt>255{ + return false + } + return true +} + +``` + ----------------------- * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)