Given an array nums
of n integers, are there elements a, b, c in nums
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.
Example:
Given array nums = [-1, 0, 1, 2, -1, -4], A solution set is: [ [-1, 0, 1], [-1, -1, 2] ]
这道题要给出所有不重复点和为0的三数和解。遍历后2个数目和,判断大小情况下,两头指针移动。
代码参考自https://leetcode.com/problems/3sum/discuss/7402/Share-my-AC-C++-solution-around-50ms-O(N*N)-with-explanation-and-comments
83
June 19, 2016 8:20 PM
class Solution {
public:vector<vector<int>> threeSum(vector<int>& nums) {
sort(nums.begin(),nums.end());
int n=nums.size();
vector<vector<int>> res;
for(int i=0;i<n-2;i++){
if(i>0 && (nums[i]==nums[i-1]) )continue;
int l=i+1, r= n-1;
while(l<r){
int sum =nums[i]+nums[l]+nums[r];
if(sum<0) l++;
else if(sum>0)r--;
else {
res.push_back(vector<int>{nums[i],nums[l],nums[r]});
while(l+1<r && nums[l]==nums[l+1])l++;
while(l<r-1 && nums[r]==nums[r-1]) r--;
l++; r--;
}
}
}
return res;
}
};