백준 1520번 C++

#include<iostream>

#include<cstring>

#include<algorithm>

using namespace std;

int m, n;

int arr[501][501];

int ans[501][501];

bool rangecheck(int x, int y) {

return x < m && x >= 0 && y < n && y >= 0;

}

int calway(int x,int y) {

pair<int,int> move[4] = { {1,0},{-1,0},{0,-1},{0,1} };

if (x == m-1 && y == n-1)

return 1;

int &answer = ans[x][y];

if (answer != -1)

return answer;

answer = 0;

for (int i = 0; i < 4; i++) {

if (rangecheck((x + move[i].first), (y + move[i].second)) && arr[x + move[i].first][y + move[i].second] < arr[x][y])

answer += calway((x + move[i].first), (y + move[i].second));

}

return answer;

}

int main(void) {

cin >> m >> n;

memset(ans, -1, sizeof(ans));

for (int i = 0; i < m; i++) {

for (int j = 0; j < n; j++) {

cin >> arr[i][j];

}

}

cout << calway(0, 0);

return 0;

}