02-线性结构4 Pop Sequence (PTA)

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.

Sample Input:

5 7 5
1 2 3 4 5 6 7
3 2 1 7 5 6 4
7 6 5 4 3 2 1
5 6 4 3 7 2 1
1 7 6 5 4 3 2

      
    

Sample Output:

YES
NO
NO
YES
NO

编译器:Python(python3)

这题的思路就是用list的append和pop来模拟堆栈,思路比较清晰,大概调试了2个小时(笑哭

M, N, K = map(int,input().split(' '))

std_list = [x for x in range(N+1)]

while K:
    K -=1
    input_list = [int(x) for x in input().split(' ')]
    stack = [0]
    i = 1
    j = 0
    while(len(stack)<=M+1):
        if stack[-1] == input_list[j]:
            stack.pop()
            j+=1
            if j == N:
                print('YES')
                break
        else:
            if i <= N:
                stack.append(std_list[i])
                i+=1
            else:
                break
    if j != N:
        print('NO')        
    

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