题解 | #三数之和#

#include <vector>
class Solution {
  public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param num int整型vector
     * @return int整型vector<vector<>>
     */
    vector<vector<int> > threeSum(vector<int>& num) {
        // write code here
        vector<vector<int>> res;
        // 3重循环
        for (int i = 0; i < num.size(); i++) {
            for (int j = i + 1; j < num.size(); j++) {
                for (int k = j + 1; k < num.size(); k++) {
                    vector<int> temp;
                    if (num[i] + num[j] + num[k] == 0) {
                        // 排序
                        // temp.push_back(num[i]);
                        // temp.push_back(num[j]);
                        // temp.push_back(num[k]);
                        int a = num[i];
                        int b = num[j];
                        int c = num[k];
                        int t = 0;
                        if (a > b) { /*如果a大于b,借助中间变量t实现a与b值的互换*/
                            t = a;
                            a = b;
                            b = t;
                        }
                        if (a > c) { /*如果a大于c,借助中间变景t实现a与c值的互换*/
                            t = a;
                            a = c;
                            c = t;
                        }
                        if (b > c) { /*如果b大于c,借助中间变量t实现b与c值的互换*/
                            t = b;
                            b = c;
                            c = t;
                        }
                        temp.push_back(a);
                        temp.push_back(b);
                        temp.push_back(c);
                        res.push_back(temp);
                    }
                }
            }
        }
        // 去重
        set<vector<int>>s(res.begin(), res.end());
        res.assign(s.begin(), s.end());
        return res;
    }
};