public class Solution {
//方法一:
    int initTargetHash(int []targethash, String Target) {
        int targetnum =0 ;
        for (char ch : Target.toCharArray()) {
            targetnum++;
            targethash[ch]++;
        }
        return targetnum;
    }
    boolean valid(int []sourcehash, int []targethash) {

        for(int i = 0; i < 256; i++) {
            if(targethash[i] > sourcehash[i])
                return false;
        }
        return true;
    }
    public String minWindow(String Source, String Target) {
        // queueing the position that matches the char in T
        int ans = Integer.MAX_VALUE;
        String minStr = "";

        int[] sourcehash = new int[256];
        int[] targethash = new int[256];

        initTargetHash(targethash, Target);
        int j = 0, i = 0;
        for(i = 0; i < Source.length(); i++) {
            while( !valid(sourcehash, targethash) && j < Source.length()  ) {
                sourcehash[Source.charAt(j)]++;
                j++;
            }
            if(valid(sourcehash, targethash) ){
                if(ans > j - i ) {
                    ans = Math.min(ans, j - i );
                    minStr = Source.substring(i, j );
                }
            }
            sourcehash[Source.charAt(i)]--;
        }
        return minStr;
    }
}

public class Solution {
    int initTargetHash(int []targethash, String Target) {
        int targetnum =0 ;
        for (char ch : Target.toCharArray()) {
            targetnum++;
            targethash[ch]++;
        }
        return targetnum;
    }

    public String minWindow(String Source, String Target) {
        // queueing the position that matches the char in T
        int ans = Integer.MAX_VALUE;
        String minStr = "";

        int[] targethash = new int[256];

        int targetnum = initTargetHash(targethash, Target);
        int sourcenum = 0;
        int j = 0, i = 0;
        for(i = 0; i < Source.length(); i++) {
            if(targethash[Source.charAt(i)] > 0)
                sourcenum++;

            targethash[Source.charAt(i)]--;
            while(sourcenum>=targetnum) {
                if(ans > i - j + 1) {
                    ans = Math.min(ans, i - j + 1);
                    minStr = Source.substring(j, i + 1);
                }
                targethash[Source.charAt(j)]++;
                if(targethash[Source.charAt(j)] > 0)
                    sourcenum--;
                j++;
            }
        }
        return minStr;
    }
}