题解 | [NOIP2002 普及组] 过河卒

#include <iostream>
using namespace std;

long long dp[26][26];

int main() 
{
    int n, m, x, y;
    cin >> n >> m >> x >> y;

    x += 1, y += 1;
    dp[0][1] = 1;

    for(int i = 1; i <= n + 1; i++)
        for(int j = 1; j <= m + 1; j++)
        {
            if(i != x && j != y && abs(x - i) + abs(y - j) == 3 || i == x && j == y)
                dp[i][j] = 0;
            else dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
        }

    cout << dp[n + 1][m + 1] << endl;
    return 0;
}