LeetCode:Restore IP Addresses

来源：互联网发布：阿里云升级配置后编辑：程序博客网时间：2024/05/29 18:13

Given a string containing only digits, restore it by returning all possible valid IP address combinations.

For example:
Given "25525511135",

return ["255.255.11.135", "255.255.111.35"]. (Order does not matter)

典型的深搜问题：

#include <iostream>#include<vector>#include <string>using namespace std;bool isValid(string s, int start, int end){if (s[start]=='0') //不能以0开头{return false;}if (end-start>3)   //防止num超出int范围溢出{return false;}int num = 0;for (int i=start;i<=end;i++){num = num*10 + s[i]-'0';}if (num<=255)     //判断数字是否有效{return true;}return false;}void DFS(string s, int curPos, int curStep, string& curIP, vector<string>& result){if (s.size()-curPos > (5-curStep)*3)   //防止出现多于四个字段的情况 如：2.5.5.2.2.5{return;}if (curPos == s.size()){curIP.erase(curIP.end()-1);  //把最后一个字段多加的‘.’弹出result.push_back(curIP);return ;}for (int i=curPos;i<s.size();++i){if (isValid(s,curPos,i)){curIP.insert(curIP.begin()+i+curStep, '.'); //压栈DFS(s,i+1,curStep+1,curIP,result);curIP.erase(curIP.begin()+i+curStep);       //出栈}}}int main(){string s="25525511035";string curIP =s;vector<string> result;DFS(s,0,1,curIP,result);return 0;}

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