Submission #17750813

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Source Code Expand

import sys
import numba
from numba import njit, b1, i4, i8, f8

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

@njit((i8, i8), cache=True)
def main(N, K):
    def f(N, n):
        # count (a, b) s.t. a + b == n
        low = max(1, n - N)
        high = min(N, n - 1)
        x = high - low + 1
        return max(x, 0)

    ans = 0
    for s in range(2, N + N + 1):
        t = s - K
        ans += f(N, s) * f(N, t)
    return ans

a, b = map(int, read().split())

print(main(a, b))

Submission Info

Judge Result