leetcode18. 4Sum

class Solution {
public:
vector<vector<int>> fourSum(vector<int>& nums, int target) {
vector<vector<int>> result = {};
vector<int> temp = {};
vector<int> temp1 = {};
if(nums.size()<4){
return result;
}
sort(nums.begin(), nums.end());
for(int i=0;i<nums.size();i++){

for(int j=nums.size() - 1;j>i;j--){
int k=i,l=j;
while(l>k){
temp = twoSum(nums, target - nums[i] - nums[j],k,l);
if(temp.size()==4){
temp1 = {};
temp1.push_back(nums[i]);//cout<<temp[0]<<temp[1]<<temp[2]<<temp[3]<<endl;
temp1.push_back(nums[j]);
temp1.push_back(temp[0]);
temp1.push_back(temp[1]);
result.push_back(temp1);
k=temp[2];
l=temp[3];
}else{
break;
}
while(nums[k] == nums[k+1] && l>k) k++;
while(nums[l] == nums[l-1] && l>k) l--;
}

while(nums[j-1] == nums[j] && j>i) j--;
}
while(nums[i] == nums[i+1] && i<nums.size()) i++;

}
return  result;
}

vector<int> twoSum(vector<int>& nums, int target,int i,int j) {
if(j-i<=2){
return vector<int>();
}
vector<int> numsCopy(nums.begin()+i+1,nums.begin()+j);//cout<<numsCopy<<endl;
//numsCopy.erase(numsCopy.begin() + i);
//numsCopy.erase(numsCopy.begin() + j-1);

//copy(numsCopy.begin(), numsCopy.end(), ostream_iterator<int>(cout, ""));cout<<endl;

vector<int>::iterator iter = numsCopy.begin();
vector<int>::iterator iter_end = numsCopy.end();
iter_end--;
while (iter != iter_end && (*iter + *iter_end) != target) {

//cout << *iter << endl;
if (*iter + *iter_end < target) {
++iter;
}
else if (*iter + *iter_end > target) {
iter_end--;
}
else {
break;
}
}
vector<int> ret = {};
if(iter == iter_end){
return ret;
}
ret.push_back(*iter);

ret.push_back(*iter_end);

ret.push_back(iter - numsCopy.begin() +i+1);

ret.push_back(iter_end - numsCopy.begin() +i+1);

return ret;
}

};