走方格的方案数

def solve(n, m):
    dp = [[0] * (m + 1) for _ in range(n + 1)]
    dp[0][0] = 1
    for i in range(n + 1):
        for j in range(m + 1):
            if i > 0:
                dp[i][j] += dp[i - 1][j]
            if j > 0:
                dp[i][j] += dp[i][j - 1]
    print(dp[n][m])