程式設計俱樂部每日一練（2018年12月7日）QAQ的小遊戲

Description

Recently,QAQ fell in love a small game,which simulates browser browsing web pages.It has three kind of operations:

1.BACK： Back to the previous page

2.FORWARD：Go to the next page

3.VISIT URL：Access to the web page

Now,QAQ has visited http://www.acm.org/

Input

There is only one test data, and the number of operations does not exceed 1000,end flag when input “QUIT”

Attion: every website length no more then 100.

Output

If the website changes, output the new website, if not, output Ignored.

Sample Input 1

VISIT http://oj.51ac.club/
VISIT http://maojunjie666.top/
BACK
BACK
BACK
FORWARD
VISIT http://www.ibm.com/
BACK
BACK
FORWARD
FORWARD
FORWARD
QUIT
Sample Output 1

http://oj.51ac.club/
http://maojunjie666.top/
http://oj.51ac.club/
http://www.acm.org/
Ignored
http://oj.51ac.club/
http://www.ibm.com/
http://oj.51ac.club/

運用二維陣列來儲存連結，通過判斷指令首字母來執行指令，VISIT則將連結存入陣列並輸出;BACK輸出前一個數組，利用索引判斷，若索引值小於0時，輸出IGNORED;FORWARD類似於BACK，索引值大於上一個VISIT引入連結的索引值時，輸出IGNORDED。
程式碼：

#include<stdio.h>
#include<string.h>
int main()
{
    char a[1001][101]={{"http://www.acm.org/"}};
    int c=0,d;
    char b[8];
    while(scanf("%s",&b)!=EOF){
        if(b[0]=='V'){
            c+=1;
            d=c;
            scanf("%s",&a[c]);
            printf("%s\n",a[c]);
        }
        else if(b[0]=='Q'){
            break;
        }
        else if(b[0]=='B'){
            if(c>=1){
                printf("%s\n",a[c-1]);
                c-=1;
            }
            else{
                printf("Ignored\n");
            }
        }
        else if(b[0]=='F'){
            if(c>=d){
                printf("Ignored\n");
            }
            else{
                printf("%s\n",a[c+1]);
                c+=1;
            }
        }
    }
    return 0;
}