#include<stdio.h>
    int main()
    {
        int i,j, n,m;
        int k,t;
        k=t=0;
        char a[100][100];
        scanf("%d",&n);
        scanf("%d",&m);
        getchar();
        for(i=0;i<n;i++)
        gets(a[i]);
        for(i=0;i<n;i++)
         puts(a[i]);
        for(i=0;i<n;i++)
        {   j=0;
            k=t=0;
            while(a[i][j]!='\0')
            {
               if(k-t>m||t>k)
                {
                    printf("NO\n");
                    break;
                }
            else
            {
                if(a[i][j]=='s')
                { k++;
                  j++;   
                }
                else if(a[i][j]=='x')
                {
                    t++;
                    j++;
                }   
            }
        }
            if (k==t)
                printf("YES\n");
            
            
        }
        
         return 0;
         }

目的是判断堆栈的合法性，s是入栈，x是出栈

好的，谢谢