leetcode 3Sum

下面这个是笨方法。

代码：

#include<iostream>
#include<algorithm>
#include<vector>

using namespace std;

vector<vector<int> > threeSum(vector<int> &num) {
    sort(num.begin(), num.end());
    vector<vector<int>> result;
    int L = num.size();
    for (int i = 0; i < L-2; i++)
    {
        if (i != 0&& num[i] == num[i - 1])
        {
            continue;
        }
        for (int j = i+1; j < L-1; j++)
        {
            int OK = 0;
            int left = j + 1;
            int right = L - 1;
            while (left <= right)
            {
                int middle = (left + right) / 2;
                int key = 0 - num[i] - num[j];
                if (num[middle] == key)
                {
                    vector<int> newV;
                    newV.push_back(num[i]);
                    newV.push_back(num[j]);
                    newV.push_back(num[middle]);
                    if (result.size() > 0)
                    {
                        if (result[result.size() - 1][0] == newV[0] && result[result.size() - 1][1] == newV[1])
                        {
                            break;
                        }
                    }
                    result.push_back(newV);
                    OK = 1;
                    break;
                }
                if (OK == 1)
                {
                    continue;
                }
                else
                {
                    if (key < num[middle])
                    {
                        right = middle-1;
                    }
                    else
                    {
                        left = middle + 1;
                    }
                }
            }
        }
    }
    return result;
}



int main()
{
    vector<int> S = { -1, 0, 1 ,2, -1, -4, - 1, };
    threeSum(S);
    return 0;
}

聪明的方法：