[LintCode] 3Sum 三数之和-白红宇

Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.

Notice

Elements in a triplet (a,b,c) must be in non-descending order. (ie, a ≤ b ≤ c)

The solution set must not contain duplicate triplets.

Have you met this question in a real interview?

Yes

Example

For example, given array S = {-1 0 1 2 -1 -4}, A solution set is:

(-1, 0, 1)(-1, -1, 2)

LeetCode上的原题，请参见我之前的博客。

class Solution {public:        /**     * @param numbers : Give an array numbers of n integer     * @return : Find all unique triplets in the array which gives the sum of zero.     */    vector
      
       
         > threeSum(vector
        
          &nums) {        vector
         
          
           > res;        sort(nums.begin(), nums.end());        for (int k = 0; k < nums.size() - 2; ++k) {            if (nums[k] > 0) break;            if (k > 0 && nums[k] == nums[k - 1]) continue;            int target = 0 - nums[k], i = k + 1, j = nums.size() - 1;            while (i < j) {                if (nums[i] + nums[j] == target) {                    res.push_back({nums[k], nums[i], nums[j]});                    while (i < j && nums[i] == nums[i + 1]) ++i;                    while (i < j && nums[j] == nums[j - 1]) --j;                    ++i; --j;                } else if (nums[i] + nums[j] < target) ++i;                else --j;            }        }        return res;    }};

本文转自博客园Grandyang的博客，原文链接：，如需转载请自行联系原博主。