机器人的运动范围

 public int movingCount(int threshold, int rows, int cols) {
        boolean [][] isState= new boolean [rows][cols]; //记录是否走过
        int sum=help( threshold,  rows,  cols,0,0,isState);
        return sum;
    }
    public int help(int k, int m, int n,int r,int c,boolean [][] isState){
        if (numSum(r)+numSum(c)>k){//如果该点数为和大于k
            return 0;
        }
        if (r<0||r>=m||c<0||c>=n){ //如果该点不在方格范围之内
            return 0;
        }
        if (!isState[r][c]){
            isState[r][c]=true;
               return help(k,m,n,r,c+1,isState)
                +help(k,m,n,r,c-1,isState)
                +help(k,m,n,r+1,c,isState)
                +help(k,m,n,r-1,c,isState)
                +1
                ;
        }else {
            return 0;
        }

    }
    public int numSum(int num){
        int res=0;
        while (num!=0){
            res+= num % 10;
            num=num/10;
        }
        return res;
    }