Submission #51932116

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Source Code Expand

import sys


def printe(*args, end="\n", **kwargs):
    print(*args, end=end, file=sys.stderr, **kwargs)


def main():
    N, M = map(int, input().split())
    patterns = []
    diff = set()
    s_idx = 1
    e_idx = N
    if N % 2 == 0:
        diff.add(N // 2)
        for _ in range(M):
            while e_idx - s_idx in diff:
                s_idx += 1
            patterns.append((s_idx, e_idx))
            diff.add(e_idx - s_idx)
            diff.add(N - e_idx + s_idx)
            s_idx += 1
            e_idx -= 1
    else:
        for _ in range(M):
            patterns.append((s_idx, e_idx))
            s_idx += 1
            e_idx -= 1

    for pt in patterns:
        print(*pt)

    # # 　シミュレーション
    # comb_ = set()
    # members = {idx: idx for idx in range(N)}

    # for _ in range(N):
    #     members_rev = {v: k for k, v in members.items()}
    #     for pt in patterns:
    #         card = (members_rev[pt[0] - 1], members_rev[pt[1] - 1])
    #         if card[1] < card[0]:
    #             card = (card[1], card[0])
    #         if card in comb_:
    #             printe(members_rev)
    #             printe(comb_)
    #             printe(card)
    #             raise ValueError
    #         comb_.add(card)

    #     for idx in range(N):
    #         members[idx] += 1
    #         members[idx] %= N


if __name__ == "__main__":
    main()

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