private int compare(int[] a,int[] b){
        if(a==null || b==null || a.length!=b.length) return 0;
        int flag = 0;
        for(int i=0;i<a.length;i++){
            int newFlag = a[i]==b[i]?0:(a[i]>b[i]?1:-1);
            if(newFlag!=0){
                if(newFlag!=flag && flag!=0) return 0;
                else flag = newFlag;
            }
        }
        return flag;
    }