利用二分法查找有序数组中某一元素
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2022-03-13 23:26:56
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1.利用二分法查找有序数组中某一元素,若有,返回下标,若没有,返回-1。
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
//int binary_search(int* a, int k)
int binary_search(int a[], int k, int sz)
{
int left = 0;
int right = sz - 1;
while (left <= right)
{
int mid = right - (right - left) / 2;
if (a[mid] == k)
{
return mid;
}
else if (a[mid] > k)
{
right = mid - 1;
}
else
{
left = mid + 1;
}
}
return -1;
}
int main()
{
int arr[] = { 1,2,3,4,5,6,7,8,9 };
int key = 6;
int sz = sizeof(arr) / sizeof(arr[0]);
int ret = binary_search(arr, key, sz);
if (-1 == ret)
printf("找不到\n");
else
printf("找到了:%d\n", ret);
system("pause");
return 0;
}
2.猜数字游戏
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>
void menu()
{
printf("******** 1.play 0.exit ********\n");
}
void game()
{
int num = 0;
int input = 0;
num = rand()%100+1;
//printf("%d\n", num);
while (1)
{
printf("请猜数字:>");
scanf_s("%d", &input);
if (num == input)
{
printf("恭喜你,猜对了\n");
break;
}
else if (input < num)
{
printf("猜小了\n");
}
else
{
printf("猜大了\n");
}
}
}
int main()
{
srand((unsigned int)time(NULL));
int input = 0;
do
{
menu();
printf("请选择:>");
scanf_s("%d", &input);
switch (input)
{
case 1:
game();
break;
case 0:
printf("退出游戏\n");
break;
default:
printf("选择错误\n");
break;
}
}
while (input);
return 0;
}
3.模拟三次输入密码的场景
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
int time = 3;
char password1[] = "123456";
char password2[10] = {0};
while(time)
{
printf("请输入密码:>");
scanf_s("%s", &password2);
if (strcmp(password1, password2) == 0)
{
printf("登录成功\n");
break;
}
else
{
;
}
time--;
}
if (time == 0)
{
printf("密码已输入三次错误,退出登录\n");
}
system("pause");
return 0;
}
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