Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that i != j, i != k, and j != k, and nums[i] + nums[j] + nums[k] == 0.
Notice that the solution set must not contain duplicate triplets.
Example :
Input: nums = [-1,0,1,2,-1,-4]
Output: [[-1,-1,2],[-1,0,1]]
Input: nums = []
Output: []
Input: nums = [0]
Output: []
public class Solution
{
public IList<IList<int>> ThreeSum(int[] nums)
{
IList<IList<int>> result = new List<IList<int>>();
if (nums == null || nums.Length < 3)
{
return result;
}
Array.Sort(nums);
for (int first = 0; first < nums.Length - 2; first++)
{
如果first是重複值就跳下一輪
if (first > 0 && nums[first] == nums[first - 1])
{
continue;
}
int second = first + 1;
int third = nums.Length - 1;
while (second < third)
{
//second重複的話一樣跳下一輪
if (nums[second] == nums[second - 1] && second > first + 1)
{
second++;
continue;
}
int sum = nums[first] + nums[second] + nums[third];
if (sum == 0)
{
result.Add(new List<int>()
{
nums[first],nums[second],nums[third]
});
second++;
third--;
}
else if (sum < 0)
{
second++;
}
else
{
third--;
}
}
}
return result;
}
}
