Question:
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.
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>> res;
void find(vector<int>& v , int s, int e , int data){
while(s < e){
int sum = v[s] + v[e] ;
if(sum == -data){
vector<int> tmp;
tmp.push_back(v[s]);
tmp.push_back(v[e]);
tmp.push_back(data);
res.push_back(tmp);
while(s != e && v[s] == v[s+1]){s++;}
while(e != 0 && v[e] == v[e-1]){e--;}
s++;
e--;
}
else if(sum < -data ){
s++;
}
else{
e--;
}
}
}
vector<vector<int>> threeSum(vector<int>& nums) {
sort(nums.begin(),nums.end());
int len = nums.size();
for(int i = 0 ; i < len ; i++){
if(i > 0 && nums[i] == nums[i-1])continue;
find(nums,i+1,len-1,nums[i]);
}
return res;
}
};