The Solution to LeetCode 15 3Sum

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.
这里的Note我在一开始想算法的时候没注意到，好像结果里边出现了重复的三个数，先贴上我的代码，不管啦！！这个改进问题留在下篇好了，警示自己先把题目读完，没读完就造成这种后果啦。
再说说思路吧，看到给出的例子，我就按照例子来想方法，思考过程的图片如下……



Answer:

class Solution {
public:
vector<vector<int> >* r;
vector<vector<int>> threeSum(vector<int>& nums) {
r= new vector<vector<int>>();
if(nums.size()<3)
{
return *r;
}

sort(nums.begin(), nums.end());

int i=0;
int j=1;
int p=2;

for (i=0,j=1;j<nums.size()-1;i++,j++)
{
for(p=2;p<nums.size();p++)
{
if(nums[i]+nums[j]+nums[p]==0)
{
vector<int> tmp;
tmp.push_back(nums[i]);
tmp.push_back(nums[j]);
tmp.push_back(nums[p]);
r->push_back(tmp);
}
}
}

return *r;
}
};

Run Code Result:


Your input

[-1,0,1,2,-1,-4]

Your answer

[[-1,-1,2],[-1,0,1],[0,1,-1]]

Expected answer

[[-1,-1,2],[-1,0,1]]