[LeetCode] 3Sum

来源：互联网发布：视频录播软件编辑：程序博客网时间：2024/06/07 21:57

class Solution {public:    vector<vector<int> > threeSum(vector<int> &num) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        vector<vector<int> > ret;        if (num.empty()) return ret;                sort(num.begin(), num.end());                for (int i = 0; i < num.size(); i++) {            if (i && num[i] == num[i - 1])                continue;                            int a = num[i];                        int j = i + 1;            int k = num.size() - 1;                        while (j < k) {                int b = num[j];                int c = num[k];                                if (a + b + c == 0) {                    vector<int> sln;                    sln.push_back(a);                    sln.push_back(b);                    sln.push_back(c);                    ret.push_back(sln);                                        for (j++; j < k && num[j] == num[j - 1]; j++);                    for (k--; j < k && num[k] == num[k + 1]; k--);                } else if (a + b + c < 0) {                    for (j++; j < k && num[j] == num[j - 1]; j++);                } else {                    for (k--; j < k && num[k] == num[k + 1]; k--);                }            }        }                return ret;    }};

Small Case: 8ms

Large Case: 288ms

Time: O(n^2)

Space: O(n)