• 15. 3Sum(C++)


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

    Note: The solution set must not contain duplicate triplets.

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

    solution :

    class Solution {
    public:
      vector<vector<int>> threeSum(vector<int>& nums) {
        int len=nums.size();
        vector<vector<int>> solution;//(m);
        std::sort(nums.begin(),nums.end());
        for(int i=0;i<len;i++){
          int sum=-nums[i];
          int left=i+1;
          int right=len-1;
          while(left<right){
            int number=nums[left]+nums[right];
            if(sum>number){
              left++;
            }else if(sum<number){
              right--;
            }else{
              vector<int> tmp(3,0);
              tmp[0]=nums[i];
              tmp[1]=nums[left];
              tmp[2]=nums[right];
              solution.push_back(tmp);
              while(left<right && nums[left]==tmp[1]) left++;
              while(left<right && nums[right]==tmp[2]) right--;
            }
          }
          while(i+1<len && nums[i]==nums[i+1]) i++;
        }
        return solution;
      }
    };




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  • 原文地址:https://www.cnblogs.com/devin-guwz/p/6498574.html
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