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unique_triplet_zero.cpp
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unique_triplet_zero.cpp
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/*
Leetcode Problem: https://leetcode.com/problems/3sum/
*/
class Solution {
public:
vector<vector<int>> threeSum(vector<int>& nums) {
// base case: min 3 elements should be there
if(nums.size() < 3)
return {};
vector<vector<int>> result;
sort(nums.begin(), nums.end());
for(int i = 0; i < nums.size() - 2; i++) {
// edge case
if(i > 0 and nums[i] == nums[i - 1])
continue;
int left = i + 1, right = nums.size() - 1;
while(left < right) {
int sum = nums[i] + nums[left] + nums[right];
// now there are 3 cases
if(sum == 0) {
result.push_back({nums[i], nums[left], nums[right]});
left++;
right--;
// avoid duplicates
while(left < right and nums[left] == nums[left - 1])
left++;
while(left < right and nums[right] == nums[right + 1])
right--;
}
else if(sum < 0)
left++;
else
right--;
}
}
return result;
}
};