PAT-数据结构专题 栈顺序

1051.栈的应用

1051 Pop Sequence

Given a stack which can keep M numbers at most. Push N numbers in the order of 1, 2, 3, ..., N and pop randomly. You are supposed to tell if a given sequence of numbers is a possible pop sequence of the stack. For example, if M is 5 and N is 7, we can obtain 1, 2, 3, 4, 5, 6, 7 from the stack, but not 3, 2, 1, 7, 5, 6, 4.

Input Specification:

Each input file contains one test case. For each case, the first line contains 3 numbers (all no more than 1000): M (the maximum capacity of the stack), N (the length of push sequence), and K (the number of pop sequences to be checked). Then K lines follow, each contains a pop sequence of N numbers. All the numbers in a line are separated by a space.

Output Specification:

For each pop sequence, print in one line "YES" if it is indeed a possible pop sequence of the stack, or "NO" if not.

m, n, k = map(int, input().split(" "))
numbers = [[i for i in map(int, input().split())] for j in range(k)]
a = [int(i) for i in range(n + 1)]
for x in range(k):
#number[x]是指输入的第x个字符串
    q = []
    j, flag = 0, 1
    for i in range(1,n + 1):
        q.append(i)
 
        if len(q) > m :
            flag = 0
            break
        while len(q) != 0 and q[-1] == numbers[x][j]:
            q.pop()
            j = j + 1
 
    if len(q) == 0 and flag == 1 :
        print("YES")
    else:
        print("NO")