백준 1937번 욕심쟁이 판다

https://www.acmicpc.net/problem/1937

#include <iostream>
#include <cmath>
using namespace std;
int dx[4] = {0, -1, 0, 1};
int dy[4] = {-1, 0, 1, 0};
int dp[501][501] = {0, };
int tree[501][501] = {0, };
int n;
bool isInner(int i, int j) {
    if (i >= 0 && i < n && j >= 0 && j < n) {
        return true;
    }
    return false;
}
int process (int x, int y) {
    
    if (dp[x][y] == 1) {
          for (int idx = 0; idx < 4; ++idx) {
            int newX = x + dx[idx];
            int newY = y + dy[idx];
            
            if (isInner(newX, newY)) {
                if (tree[x][y] < tree[newX][newY]) {
                    dp[x][y] = max(dp[x][y], process(newX, newY) + 1);
                }
            }
        }  
    }
    return dp[x][y];
}
int main()
{
    int result = -1;
    cin >> n;
    
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            cin >> tree[i][j];
            dp[i][j] = 1;
        }
    }
    
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            result = max(result, process(i, j));
        }
    }
    
    cout << result << endl;
}