题解 | 区间翻转

def solve(testcase):
    n, k = MI()
    q = deque()
    cur = 1
    res = []

    cl, cr = 0, 0
    flag = True
    for _ in range(k):
        l, r = GMI()
        if flag:
            while cr <= r:
                q.append(cur)
                cur += 1
                cr += 1
            while cl < l:
                res.append(q.popleft())
                cl += 1
        else:
            while cr <= r:
                q.appendleft(cur)
                cur += 1
                cr += 1
            while cl < l:
                res.append(q.pop())
                cl += 1
        flag = not flag
    
    if flag:
        while cur <= n:
            q.append(cur)
            cur += 1
        while q:
            res.append(q.popleft())
    else:
        while cur <= n:
            q.appendleft(cur)
            cur += 1
        while q:
            res.append(q.pop())
    
    print(*res) 

for testcase in range(1):
    solve(testcase)