题解 | 星环

import sys
from math import inf

def solve():
    # num二进制，从k+1找，1，最接近；2，距离最短
    input = sys.stdin.readline
    k, m = list(map(int, input().split()))
    nums = list(map(int, input().split()))
    n = len(nums)
    bits = []
    for num in nums:
        x = bin(num)[2:].zfill(8)[::-1]
        bits.extend(list(map(int, x)))
    # print(bits)
    bits_len = len(bits)
    seg = []
    i = 0
    while i < bits_len:
        if bits[i]:
            j = i
            while j < bits_len and bits[j] == 1:
                j += 1
            seg.append([i, j - i])
            i = j
        else:
            i = i + 1
    # 需要把首尾合并一下
    if bits[0] == 1 and bits[bits_len-1] == 1:
        size = seg[0][1]
        seg[-1][1] += size
        seg.pop(0)
    pos = -1
    mn_size = inf
    dis_mn = inf
    for i, size in seg:
        if size < k:
            continue
        if i > m:
            dis = i - m
        else:
            dis = (i + 8 * n) - m

        if size < mn_size:
            pos = i
            mn_size = size
            dis_mn = dis
 
        if size == mn_size and dis < dis_mn:
            pos = i
            dis_mn = dis         

    print(pos)


if __name__ == "__main__":
    solve()