题解 | 抽卡(python)
抽卡
https://www.nowcoder.com/practice/cddfb87d552c468d9176e95efffa7b3c
import sys
MOD = 10**9 + 7
def modinv(x):
return pow(x, MOD-2, MOD) # 快速幂
def solve():
n = int(input())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
prod_a = 1
prod_a_minus_b = 1
for i in range(n):
prod_a = prod_a * a[i] % MOD
prod_a_minus_b = prod_a_minus_b * (a[i] - b[i]) % MOD
num = (prod_a - prod_a_minus_b) % MOD
den = prod_a
ans = num * modinv(den) % MOD
print(ans)
if __name__ == "__main__":
solve()
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