标签:blog io os ar for sp div on 问题
类似3Sum,先排序,这后两重for循环,然后对最后的一个数组设两个指针遍历。这里注意重复的问题,例如第一重如果和前面一个数相同则跳过,因为前面的查找肯定包含了本次的情况。
// 4Sum.cpp : 定义控制台应用程序的入口点。 // #include "stdafx.h" #include <vector> #include <algorithm> #include <map> #include <iostream> using namespace std; class Solution { public: vector<vector<int> > fourSum(vector<int> &num, int target) { sort(num.begin(),num.end()); vector<vector<int>>res; if (num.size() < 4) return res; for (int i = 0; i < num.size()-3; i++) { if (i>0 && num[i] == num[i - 1]) continue; for (int j = i + 1; j < num.size() - 2; j++) { if (j>i + 1 && num[j] == num[j - 1]) continue; int p1 = j + 1,p2=num.size()-1; int sum = target - num[i] - num[j]; while (p1 < p2) { if (p1>j + 1 && num[p1] == num[p1 - 1]) { p1++; continue; } if (p2<num.size()-1&&num[p2] == num[p2 + 1]) { p2--; continue; } if (p1 >= p2) { break; } if (num[p1] + num[p2] == sum) { vector<int>tempV; tempV.push_back(num[i]); tempV.push_back(num[j]); tempV.push_back(num[p1]); tempV.push_back(num[p2]); res.push_back(tempV); p2--; } else if (num[p1]+num[p2]>sum) { p2--; } else{ p1++; } } } } return res; } }; int _tmain(int argc, _TCHAR* argv[]) { Solution ss; vector<int>test; test.push_back(1); test.push_back(0); test.push_back(-1); test.push_back(0); test.push_back(-2); test.push_back(2); vector<vector<int> > res = ss.fourSum(test,0); for (int i = 0; i < res.size(); i++) { for (int j = 0; j < res[i].size(); j++) cout << res[i][j] << ","; cout << endl; } system("pause"); return 0; }
标签:blog io os ar for sp div on 问题
原文地址:http://www.cnblogs.com/supernigel/p/4029114.html