Title
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]
]
Solution
//cpp:
class Solution {
public:
vector<vector<int>> threeSum(vector<int>& nums) {
vector<vector<int>> res;
sort(nums.begin(), nums.end());
for (int i = 0; i < nums.size(); i++) {
if (i == 0 || (i > 0 && nums[i] != nums[i - 1])) {
int lo = i + 1, hi = nums.size() - 1, sum = 0 - nums[i];
while (lo < hi) {
if (nums[lo] + nums[hi] == sum) {
res.push_back({ nums[lo],nums[hi], nums[i] });
while (lo < hi&&nums[lo] == nums[lo + 1]) lo++;
while (lo < hi&&nums[hi] == nums[hi - 1]) hi--;
lo++, hi--;
}
else if (nums[lo] + nums[hi] < sum) {
lo++;
}
else {
hi--;
}
}
}
}
return res;
}
};