C Primer Plus8-5

/*5，修改程序清单 8,4 中的猜测程序，使其使用更智能的猜测策略。例如，程序最初猜 50，让其
询问用户该猜测值是大、小还是正确。如果该猜测值小，则令下一次猜测值为 50 和 100 的中值，也就是
75。如果 75 大，则下一次猜测值为 75 和 50 的中值，等等。使用这种二分搜索(binary search)策略，起
码如果用户没有欺骗，该程序很快会获得正确答案。*/

#include<stdio.h>
#include<stdlib.h>

int main()
 {
     char a;
     int guess;
     int max = 100, min = 1;

     printf("Pick an intger from 1 to 100.I will try to guess ");
     printf("it.\nRespond with a y if my guess is right and with");
     printf("\na < if it is smaller and a > it is bigger.\n");
     printf("Uh...is your number %d?\n", guess = (max + min) / 2);

     while ((a = getchar()) != 'y')//获取用户相应并和y比较
      {
          if (a == '<')
           {   
               min = guess;
               printf("Well,then,is it %d?", guess = (min + max) / 2); 
           }

          else if (a == '>')
           {   
               max = guess;
               printf("Well,then,is it %d?", guess = (max + min) / 2);

           }
      }

     printf("I knew I could do it!\n");
     system("pause");
     return 0;

 }