剑指offer--48.机器人的运动范围

class Solution {
    public:
        int movingCount(int threshold, int rows, int cols) {
            if(threshold<0) return 0;
            row = rows;
            col = cols;
            ct= 1 ;
            memset(ma, 0, sizeof(ma));
            ma[0][0] = 1;
            dfs(threshold,0,0);
            return ct;
        }
        void dfs(int k, int rr ,int cc) {
            for(int i=0; i<4; i++) {
                int c = dir[i][0] + cc;
                int r = dir[i][1] + rr;
                if(ma[r][c]==1 || c <0 || r<0 || c>=col || r>=row || sum_n(c, r) > k) continue;
                ma[r][c] = 1;
                ++ct; 
                dfs(k, r, c);
            }
        }
        int sum_n(int a, int b) {
            int sumab = 0;
            while (a != 0) {
                sumab += a%10;;
                a /= 10;
            }
            while (b != 0) {
                sumab += b%10;;
                b /= 10;
            }
            return sumab;
        }
    private:
        int dir[4][2] = {{0,1},{0,-1},{1,0},{-1,0}};
        int ma[80][80];
        int row, col, ct;
};