BOJ 1520 - 내리막 길 [C++]

문제

링크

풀이

#include <iostream>
#include <vector>
using namespace std;
 
int m, n;
vector<vector<int> > a, dp;
vector<vector<bool> > visited;
 
int dfs(int x, int y) {
  if (x == m-1 && y == n-1) return 1;
  if (visited[x][y]) return dp[x][y];
  visited[x][y] = true;
 
  if (x > 0 && a[x-1][y] < a[x][y]) dp[x][y] += dfs(x-1, y);
  if (x < m-1 && a[x+1][y] < a[x][y]) dp[x][y] += dfs(x+1, y);
  if (y > 0 && a[x][y-1] < a[x][y]) dp[x][y] += dfs(x, y-1);
  if (y < n-1 && a[x][y+1] < a[x][y]) dp[x][y] += dfs(x, y+1);
  return dp[x][y];
}
 
void solve(void) {
  cin >> m >> n;
  a.resize(m, vector<int>(n));
  dp.resize(m, vector<int>(n, 0));
  visited.resize(m, vector<bool>(n, false));
  for (int i=0; i<m; i++) {
    for (int j=0; j<n; j++) {
      cin >> a[i][j];
    }
  }
 
  cout << dfs(0, 0);
}
 
int main(void) {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
 
  solve();
  return 0;
}