题解 | 二维斐波那契数列

x = input().split(" ")
n, m = int(x[0]), int(x[1])
dp = [[0] * (m + 1) for _ in range(n + 1)] # 初始化二维数组

dp[1][1] = 1
for i in range(2, n + 1):
    dp[i][1] = dp[i - 1][1]

for i in range(2, m + 1):
    dp[1][i] = dp[1][i - 1]

for i in range(2, n + 1):
    for j in range(2, m + 1):
        dp[i][j] = dp[i - 1][j] + dp[i][j - 1]
        dp[i][j] = int(dp[i][j]%(1e9 + 7))
    
print(int(dp[n][m] % (1e9 + 7)))