线性结构3 Pop Sequence（PAT）

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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 51 2 3 4 5 6 73 2 1 7 5 6 47 6 5 4 3 2 15 6 4 3 7 2 11 7 6 5 4 3 2

Sample Output:

YESNONOYESNO

题意

第一行输入 M, N，T

M代表栈的容量，N为序列长度，T为测试组数

我们可以向容量为M的栈中按照1 ， 2， 3..的顺序推入 1 ，2, 3.. ，可以任意弹出。问能否输出给定序列。

样例 5 6 4 3 7 2 1

推入 1 2 3 4 5 ，弹出 5，此时 1 2 3 4

输入 6 ，推入 6，此时 1 2 3 4 6 ，弹出6 ，此时 1 2 3 4

输入 4 ，弹出 4，此时 1 2 3

输入 3 ，弹出 3，此时 1 2

输入 7，推入 7 ，此时 1 2 7，弹出 7，此时 1 2

输入 2，弹出 2 ，此时 1

输入1 ，弹出 1. 输出 YES！

直接模拟题意解决

#include<iostream>#include<cstdio>#include<stack>using namespace std;int main(){int n,m,t;scanf("%d%d%d",&n,&m,&t);stack<int>st;for(int i = 0;i<t;i++){int tmp = 1;bool False = 0;for(int j=0;j<m;j++){int input ;scanf("%d",&input);while(st.size() <= n && !False){ //满足条件就不断推入 1,2,3...if(st.empty() || st.top() != input)st.push(tmp++);else if(st.top() == input){ //如果栈顶元素与输入的一样了，就弹出。st.pop(); break;}if(st.size() > n){False =  1; break; //超过栈的范围了}}}if(!False)printf("YES\n");elseprintf("NO\n");while(!st.empty())st.pop();}return 0;}

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