判断出栈序列是否合法（c语言实现）

素颜马尾好姑娘i 2021-11-10 06:48 321阅读 0赞

### 题目 ###

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

### 代码 ###

#include <stdio.h>  
    #define maxn 1005  
    int stack[maxn];  
    int out[maxn];  
    int check(int m,int n) 
    {  
        int po=0,top=0;  
        for(int i=1;i<=n;i++)  
        {  
            for(int j=po+1;j<=out[i];j++)  
            {  
                po=j;  
                stack[top++]=j;  
    			if(top>m) return 0; 	
            }  
            if(stack[--top]!=out[i])  
    			return 0;  
        }  
        return 1;  
    }  
    int main()  
    {  
        int m,n,k;  
        scanf("%d %d %d",&m,&n,&k);
    	while(k--){
    		for(int i=1;i<=n;i++){  
    			scanf("%d",&out[i]);  
    		}  
    		if(check(m,n))  
    			printf("YES\n");  
    		else  
    			printf("NO\n"); 	
    	}
        return 0;  
    }

### 结果 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNzU1MTAzNg_size_16_color_FFFFFF_t_70]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNzU1MTAzNg_size_16_color_FFFFFF_t_70]: /images/20211109/a4c84bab7dc94d5bbcc83153b5aa5e45.png