poj1363

http://poj.org/problem?id=1363

通过栈模拟，检验有无可能实现输入和输出

#include<stdio.h>
 int sum;
int *in,*out,*stack;
int inpoint,outpoint,stackpoint;
int is_ok()
{
    inpoint=-1,outpoint=0,stackpoint=-1;
    while(outpoint<sum)
    {
        if(stackpoint>-1)
        {
            while(out[outpoint]!=stack[stackpoint]&&inpoint<sum)
             stack[++stackpoint]=in[++inpoint];
            if(inpoint<sum)
            {
                outpoint++;
                stackpoint--;
            }
            else return 0;
        }
        else
        {
            if(inpoint<sum) stack[++stackpoint]=in[++inpoint];
            else return 0;
        }
    }
    return 1;
}
void ini()
{
    while(scanf("%d",&sum)==1&&sum)
    {
        in=new int [sum];
        out=new int [sum];
        stack=new int [sum];
        while(scanf("%d",&out[0])==1&&out[0])
        {
            for(int i=1;i<sum;i++) scanf("%d",&out[i]);
            for(int i=1;i<=sum;i++) in[i-1]=i;
            if(is_ok()) printf("Yes\n");
            else printf("No\n");
        }
        printf("\n");
    }
}
int main()
{
    ini();
    return 0;
}