bnuoj 29373 Key Logger（模拟双向队列）

http://www.bnuoj.com/bnuoj/problem_show.php?pid=29373

【题意】：模拟光标输入

【题解】：用双向列表模拟实现，这里用其他模拟会超时，注意内存的释放

【code】：

#include <iostream>
#include <stdio.h>
#include <math.h>
#include <algorithm>
#include <list>
#include <string>
#include <string.h>

using namespace std;

struct Nod
{
    char ch;
    Nod * second;
    Nod * first;
    Nod()
    {
        second=NULL;
        first=NULL;
        ch=0;
    }
};
Nod * head,*tail,*now,*temp;

char str[1000010];

int main()
{
    int t,cas=1;
    scanf("%d",&t);
    while(t--)
    {
        int i;
        scanf("%s",str);
        int len = strlen(str);
        head = new Nod;
        tail = new Nod;
        head->second = tail;
        tail->first = head;
        now = head;
        int pos = 0;
        for(i=0;i<len;i++)
        {
            char ch = str[i];
            if(ch=='<')
            {
                if(now!=head)
                {
                    now = now->first;
                  //  cout<<" sdfsd"<<endl;
                }
            }
            else if(ch=='>')
            {
                if(now->second!=tail)
                {
                    now = now->second;
                }
            }
            else if(ch=='-')
            {
                if(now!=head)
                {
                    now->first->second = now->second;
                    now->second->first = now->first;
                    temp = now;
                    free(temp);
                    now = now->first;
                }
            }
            else
            {
                temp = new Nod;
                temp->ch = ch;
                now->second->first = temp;
                temp->second =now->second;
                now->second = temp;
                temp->first = now;
                now = now->second;
            }
        }
        now = head->second;
        printf("Case %d: ",cas++);
        while(now!=tail)
        {
            printf("%c",now->ch);
            now = now->second;
            free(now->first);
        }
        free(now);
        putchar(10);
    }
    return 0;
}