public class Solution {

public String minWindow(String S, String T) {

// Start typing your Java solution below

// DO NOT write main() function

int start = 0;

int end = 0;

int n =0;

int min = Integer.MAX_VALUE;

int minstart = 0;

int minend = 0;

HashSet<Character> hs = new HashSet<Character>();

int count[] = new int[300];

int sta[] = new int[300];

for(int i=0;i<T.length();i++){

hs.add(T.charAt(i));

sta[T.charAt(i)+0]++;

}

int target = hs.size();

boolean found = false;

while(end<S.length()){

while(n<target && end < S.length()){

if(!hs.contains(S.charAt(end))){

end++;

}else{

count[S.charAt(end)+0]++;

if(count[S.charAt(end)+0]==sta[S.charAt(end)+0]){

n++;

}

end++;

}

}

if(min>end+1-start && n==target){

found = true;

min = end+1-start;

minend = end;

minstart = start;

}

while(n==target && start<=end){

if(!hs.contains(S.charAt(start))){

start++;

}else{

if(count[S.charAt(start)+0]==sta[S.charAt(start)+0]){

n--;

}

count[S.charAt(start)+0]--;

start++;

}

}

if(min>end+2-start){

min = end+2-start;

minend = end;

minstart = start-1;

}

}

if(!found){

return "";

}

return S.substring(minstart,minend);

}

}