题解 | 二维斐波那契数列

MOD = 10**9 + 7
m,n = map(int,input().split())
dp = [[0]*(m+1) for _ in range(n+1)]

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

print(dp[n][m])