class Solution {
    public String minWindow(String s, String t) {
        boolean[] chs=new boolean[128];
        int[] cnt=new int[128];
        for(int i=0;i<t.length();i++)
        {
            cnt[t.charAt(i)]++;
            chs[t.charAt(i)]=true;
        }
        int count=t.length();
        
 
int l=0;
        int r=0;
        int end=Integer.MAX_VALUE;
        int start=0;
        while(r<=s.length()&&l<s.length())
        {
            if(count>0&&r<s.length())
            {
                if(chs[s.charAt(r)]==true&&cnt[s.charAt(r)]>0)
                    count
 
--;
                cnt[s.charAt(r)]--;
                r++;
            }
            else if(count<=0)
            {
                if(r-l<end-start)
                {
                    start=l;
                    end=r;
                }
                cnt[s.charAt(l)]++;
                
 
if(chs[s.charAt(l)]==true&&cnt[s.charAt(l)]>0)
                    count++;
                l++;
            }
            else
                break;
        }
        if(end==Integer.MAX_VALUE)
            return "";
        return s.substring(start, end);
    }
}

76. Minimum Window Substring