Submission #7090930

---

Source Code Expand

#!/usr/bin/env python3
n, d = map(int, input().split())
x, y = map(lambda t: abs(int(t)), input().split())
k = x // d + y // d
if x % d != 0 or y % d != 0 or n < k or (n - k) % 2 != 0:
    print(0)
    exit()
x //= d
y //= d
p = [[0] * (n + 1) for _ in range(n + 1)]
p[0][0] = 1
for i in range(n):
    p[i + 1][0] = p[i][0] / 2
for i in range(n):
    for j in range(i + 1):
        p[i + 1][j + 1] = (p[i][j] + p[i][j + 1]) / 2
ans = 0
for i in range(n + 1):
    j = n - i
    tmp = 1
    tmp *= p[n][i]
    tmp *= p[i][(i + x) // 2]
    tmp *= p[j][(j + y) // 2]
    ans += tmp
print(ans)

Submission Info

Judge Result