void DLL::push_after(int val,int after){
LI::iterator it=find(after);
if(it!=dt.end()){
++it;
dt.insert(it,val);
}
}
/**
* @param numbers: Give an array numbersbers of n integer
* @param target: you need to find four elements that's sum of target
* @return: Find all unique quadruplets in the array which gives the sum of
* zero.
*/
LLI fourSum(LI nums, int target) {
sort(nums.begin(), nums.end());
LLI res;
LI set;
fourSum(res, set, nums, 0, target);
return res;
}
void combine(LLI &results, LI &set, LI &candidates, int k, int target) {
int sum = 0;
for (int x : set)
sum += x;
if (sum == target) {
LI sorted = set;
sort(sorted.begin(), sorted.end());
results.push_back(sorted);
return;
}
if (target < sum)
return;
for (int i = k; i < candidates.size(); ++i) {
set.push_back(candidates[i]);
combine(results, set, candidates, i, target);
set.pop_back();
}
}
void DLL::del(int val){
LI::iterator it=find(val);
if(it!=dt.end()) dt.erase(it);
}
LI::iterator DLL::find(int val){
LI::iterator it;
for(it=dt.begin();it!=dt.end();++it)
if((*it) == val) return it;
return it;
}
void DLL::print(){
LI::iterator it;
for(it=dt.begin();it!=dt.end();++it)
cout << (*it) << "->";
cout << "NULL" << endl;
}