보행자 천국 C++

#include <vector>
#include <cstring>

using namespace std;
const int MAX = 501;
int MOD = 20170805;
int top[MAX][MAX],lefts[MAX][MAX];

int solution(int m, int n, vector<vector<int>> city_map) {
    memset(top,0,sizeof(top));
    memset(lefts,0,sizeof(lefts));
    
    top[1][1] = lefts[1][1] = 1;
      for(int i=1; i<=m; i++){
        for(int j=1; j<=n; j++){
            if(city_map[i-1][j-1] == 0){
                top[i][j] += (top[i-1][j] + lefts[i][j-1])%MOD;
                lefts[i][j] += (top[i-1][j] + lefts[i][j-1])%MOD;
            }
            else if(city_map[i-1][j-1] == 1){
                top[i][j] = 0;
                lefts[i][j] = 0;
            }
            else{
                top[i][j] = top[i-1][j];
                lefts[i][j] = lefts[i][j-1];
            }
        }
      }
	return top[m][n]%MOD;
}