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。使用二分搜索策略。

/*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。使用二分搜索策略*/
#include <stdio.h>
int main(void)
{
	char ch;
	int guess = 50;
	int min = 1;
	int max = 100;
	
	printf("pick an integer from 1 to 100. I will try to gusse ");
	printf("it.\nRespond with a y or b or s (s mines small, b mines big, y mines yes) ");
	printf("Uh...is your number %d?\n", guess);
	while ((ch = getchar()) != 'y')
	{
		if (ch == 'b')
		{
			max = guess;
			guess = (max + min)/2;
			printf("well then is %d?\n", guess);
		}
		if (ch == 's')
		{
			min = guess;
			guess = (max + min)/2;
			printf("well then is %d?\n", guess);
		}
		if (ch != 's' && ch != 'b' && ch != 'y')
			printf("sorry, I understand only y or s or b.\n");
		while ((ch = getchar())!= '\n')
			continue;
	}
	printf("I know I could do it!\n");

return 0;
}