From 78ae0f196cc279110f655e4614cfe469ea0c75b6 Mon Sep 17 00:00:00 2001
From: Yuhao Ju <juguaguaji@gmail.com>
Date: Thu, 8 Dec 2022 21:14:57 +0800
Subject: [PATCH] =?UTF-8?q?update=200093.=E5=A4=8D=E5=8E=9FIP=E5=9C=B0?=
 =?UTF-8?q?=E5=9D=80:=20=E6=9B=BF=E6=8D=A2=20go=20=E4=BB=A3=E7=A0=81?=
MIME-Version: 1.0
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---
 problems/0093.复原IP地址.md | 78 +++++++++++++++------------------
 1 file changed, 36 insertions(+), 42 deletions(-)

diff --git a/problems/0093.复原IP地址.md b/problems/0093.复原IP地址.md
index ce62cac1..97178cd5 100644
--- a/problems/0093.复原IP地址.md
+++ b/problems/0093.复原IP地址.md
@@ -424,6 +424,42 @@ class Solution:
         return True
 ```
 
+## Go 
+
+```go
+var (
+    path []string
+    res  []string
+)
+func restoreIpAddresses(s string) []string {
+    path, res = make([]string, 0, len(s)), make([]string, 0)
+    dfs(s, 0)
+    return res
+}
+func dfs(s string, start int) {  
+    if len(path) == 4 {    // 够四段后就不再继续往下递归
+        if start == len(s) {      
+            str := strings.Join(path, ".")
+            res = append(res, str)
+        }
+        return 
+    }
+    for i := start; i < len(s); i++ {
+        if i != start && s[start] == '0' { // 含有前导 0，无效
+            break
+        }
+        str := s[start : i+1]
+        num, _ := strconv.Atoi(str)
+        if num >= 0 && num <= 255 {
+            path = append(path, str)  // 符合条件的就进入下一层
+            dfs(s, i+1)
+            path = path[:len(path) - 1]
+        } else {   // 如果不满足条件，再往后也不可能满足条件，直接退出
+            break
+        }
+    }
+}
+```
 
 ## JavaScript
 
@@ -494,48 +530,6 @@ function restoreIpAddresses(s: string): string[] {
 };
 ```
 
-## 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;i<len(s);i++{
-		//处理
-		path:=append(path,s[startIndex:i+1])
-		if i-startIndex+1<=3&&len(path)<=4&&isNormalIp(s,startIndex,i){
-			//递归
-			backTracking(s,path,i+1,res)
-		}else {//如果首尾超过了3个，或路径多余4个，或前导为0，或大于255，直接回退
-			return
-		}
-        //回溯
-		path=path[:len(path)-1]
-	}
-}
-func isNormalIp(s string,startIndex,end int)bool{
-	checkInt,_:=strconv.Atoi(s[startIndex:end+1])
-	if end-startIndex+1>1&&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
-}
-
-```
-
 ## Rust
 
 ```Rust