折半查找与猜数字游戏

1.折半查找

#include
int main()
{
	int arr[] = {1,2,3,4,5,6,7,8,9,10};
	int key = 7;
	int left = 0;
	int right = sizeof(arr)/sizeof(arr[0])-1;
	while(left<=right)
	{
		int mid = left+(right-left)/2;
		if(arr[mid] < key)
		{
			left = mid+1;
		}
		else if(arr[mid]>key)
		{
			right = mid-1;
		}
		else
		{
			printf("找到了，下标为:");
			printf("%d\n", mid);
			break;
		}
	}
	if(left>right)
	{
		printf("找不到\n");
	}
	return 0;
}

2.猜数字游戏

#include
#include 
void menu()
{
	printf("1.play 0.exit\n");
}
void play_game()
{
	int rand_num = rand()%100;
	int tmp = 0;
	while(1)
	{
		printf("请输入你猜的数字");
		scanf("%d", &tmp);
		if(tmp == rand_num)
		{
			printf("猜对了\n");
			break;
		}
		else if(tmp > rand_num)
		{
			printf("猜大了\n");
		}
		else
		{
			printf("猜小了\n");
		}
	}
}
int main()
{
	int input = 0;
	srand((unsigned int)time(NULL));
	do
	{
		menu();
		printf("请选择");
		scanf("%d", &input);
		switch(input)
		{
		case 1:
			play_game();
			break;
		case 0:
			exit(EXIT_SUCCESS);
			break;
		default:
			printf("选择错误\n");
			break;
		}
	} while (input);
	
	return 0;
}