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] ]
AC code:
class Solution {
public:
vector<vector<int>> threeSum(vector<int>& nums) {
int len = nums.size();
vector<vector<int> > v;
sort(nums.begin(), nums.end());
int front, tear, target, sum;
for (int i = 0; i < len; ++i) {
target = -nums[i];
front = i + 1;
tear = len-1;
while (front < tear) {
sum = nums[front] + nums[tear];
if (sum < target) {
front++;
} else if (sum > target) {
tear--;
} else {
vector<int> sub_ans(3, 0);
sub_ans[0] = nums[i];
sub_ans[1] = nums[front];
sub_ans[2] = nums[tear];
v.push_back(sub_ans);
while (front < tear && nums[front] == sub_ans[1])
front++;
while (front < tear && nums[tear] == sub_ans[2])
tear--;
}
}
while ((i+1) < len && nums[i] == nums[i+1]) {
i++;
}
}
return v;
}
};
原文：https://www.cnblogs.com/ruruozhenhao/p/9733476.html