126 周赛

第三题

最后想出思路了，但没实现，同时思路也没题解那么清晰。

s0 = "DKER EPH VOS GOLNJ ER RKH HNG OI RKH UOPMGB CPH VOS FSQVB DLMM VOS QETH SQB"
a = "DKER EPH VOS GOLNJ UKLMH QHNGLNJ A"
b = "AB CPH VOS FSQVB DLMM VOS QHNG A"
c = "AB"
INF = int(1e18)
N = int(1e5 + 1)
length = [len(s0)] + [None] * N

for i in range(1, N + 1):
    length[i] = len(a) + len(b) + len(c) + length[i-1] * 2
    length[i] = min(length[i], INF)

q = int(input())

def solve(n, k):
    # if k > length[n]:
    #     return '.'
    # if n == 0:
    #     return s0[k - 1]

    # if k <= len(a):         return a[k - 1]
    # k -= len(a)
    # if k <= length[n-1]:    return solve(n-1, k)
    # k -= length[n-1]
    # if k <= len(b):         return b[k - 1]
    # k -= len(b)
    # if k <= length[n-1]:    return solve(n-1, k)
    # k -= length[n-1]

    # return c[k - 1]

    while True:
        if k > length[n]:
            return '.'
        if n == 0:
            return s0[k - 1]

        if k <= len(a):
            return a[k - 1]

        k -= len(a)
        if k <= length[n-1]:
            n -= 1
            continue

        k -= length[n-1]
        if k <= len(b):
            return b[k - 1]

        k -= len(b)
        if k <= length[n-1]:
            n -= 1
            continue

        k -= length[n-1]
        return c[k - 1]


for _ in range(q):
    n, k = list(map(int, input().split()))
    print(solve(n, k), end='')