leetcode minimum window substring

class Solution {
public:
bool findAll(vector<int> to_find,vector<int> has_find){
bool flag=true;
for(int i=0;i<256;i++){
if(to_find[T[i]]<=has_find[T[i]]){
flag=flag&&true;
}
else{
flag=false;
break;
}
}
return flag;
}
string minWindow(string S, string T) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
int lenT=T.length();
int lenS=S.length();
if(lenT==0)
return "";
if(lenS==0)
return "";
vector<int> to_find(256);
vector<int> has_find(256);
for(int i=0;i<lenT;i++){
to_find[T[i]]++;
}
int left=0;
int minleft=0;
int minLength=INT_MAX;
for(int i=0;i<lenS;i++){
if(to_find[S[i]]>0){
has_find[S[i]]++;
//cout<<S[i];
if(findAll(to_find,has_find)){//window contains all chars in T,then move left
//assert(S[i]=='b');
//cout<<"in"<<endl;
//cout<<S[i]<<endl;
while(true){//move left
//cout<<has_find[S[left]]<<endl;
//cout<<to_find[S[left]]<<endl;
if(has_find[S[left]]<=to_find[S[left]]&&has_find[S[left]]!=0){//condition is left is redundant
break;
}
//cout<<"in"<<endl;
if(has_find[S[left]]!=0)
has_find[S[left]]--;//
left++;
}
if(minLength>(i-left+1)){//see if minlength

minLength=i-left+1;
minleft=left;
}
//has_find[S[left]]--;
//left++;
//cout<<S[left]<<endl;
}
}
}
if(minLength==INT_MAX){

return "";
}
else{

//cout<<minleft<<minLength;
return S.substr(minleft,minLength);
}
}
};