leetcode18

bool cmp(const int&a ,const int&b)
{
	return a < b;
}
class Solution {
public:
    vector< vector<int> > fourSum(vector<int>& nums, int target) {
		int len = nums.size();
		int i;
		int j;
		int k;
		int l;
		vector< vector<int> >result;
		vector<int>temp;
		if(len < 4)
		{
			return result;
		}
		sort(nums.begin(),nums.end(),cmp);
		for(i=0;i<len-3;i++)
		{
			for(j=i+1;j<len-2;j++)
			{
				k=j+1;
				l=len-1;
				while(k<l)
				{
					if(nums[i]+nums[j]+nums[k]+nums[l]==target)
					{
						temp.push_back(nums[i]);
						temp.push_back(nums[j]);
						temp.push_back(nums[k]);
						temp.push_back(nums[l]);
						result.push_back(temp);
						temp.clear();
						while(k<l&&nums[k]==nums[k+1])
						    k++;
					    while(k<l&&nums[l]==nums[l-1])
						    l--;
					}
					if(nums[i]+nums[j]+nums[k]+nums[l] < target)
					{
						k++;
					}
					else
					{
						l--;
					}
				}
				while(j<len-2&&nums[j]==nums[j+1])
					j++;
			}
			while(i<len-3&&nums[i]==nums[i+1])
				i++;
		}
		return result;
	}
};