题解 | #三数之和#

#include <vector>
#include <algorithm>

class Solution {
public:
    vector<vector<int> > threeSum(vector<int>& num) {
        vector<vector<int> > res;
        sort(num.begin(), num.end());
        
        for (int i = 0; i < num.size(); i++) {
            if (i  && num[i] == num[i - 1])
                continue;

            int target = 0 - num[i];
            int j = i + 1;
            int k = num.size() - 1;
            
            while (j < k) {
                if (num[j] + num[k] < target) {
                    j++;
                } else if (num[j] + num[k] > target) {
                    k--;
                } else {
                    res.push_back({num[i], num[j], num[k]});
                    while (j < k && num[j] == num[j + 1])
                        j++;
                    while (j < k && num[k] == num[k - 1])
                        k--;
                    j++;
                    k--;
                }
            }
        }
        
        return res;
    }
};