#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
//二维数组逆置====================================
int main10()
{
int matrix[3][3] = {
{1,2,3},
{4,5,6},
{7,8,9}
};
printf(“逆置前数组：\n”);
for (int i = 0;i < 3;i++)
{
for (int j = 0;j < 3;j++)
{
printf(“%d”, matrix[i][j]);
}
printf(“\n”);
}
for (int i = 0;i < 3;i++)
{
for (int j = i + 1;j < 3;j++)
{
int tmp = matrix[i][j];
matrix[i][j] = matrix[j][i];
matrix[j][i] = tmp;
}
}
printf(“逆置后数组：\n”);
for (int i = 0;i < 3;i++)
{
for (int j = 0;j < 3;j++)
{
printf(“%d”, matrix[i][j]);
}
printf(“\n”);
}
return 0;
}
//二分查找法======================================
int main9()
{
int arr[] = { 1,2,5,6,9,11,15,36,38,45,49,58,68,69,80,88,90,98,99,100};
int len = sizeof(arr) / sizeof(arr[0]);
int i = 0;
int j = len - 1;
int mid;
int n;
printf(“请输入要找的key:”);
scanf(“%d”, &n);
int key = n;
while (i <= j)
{
mid = i + (j - i) / 2;//最好使用mid = i+(j-i)/2 防止数据溢出
//不用mid = ((i + j) / 2)
if (arr[mid] < key)
{
i = mid + 1;
}
else if (arr[mid] > key)
{
j = mid - 1;
}
else
{
printf(“找到了key!\narr[%d]=%d\n”, mid, key);
return 0;
}
}
printf(“没找到哦。。。。”);
return 0;
}
//数组逆置========================================
int main8()
{
int arr[] = {1,2,3,4,5};
int len = sizeof(arr) / sizeof(arr[1]);
int i = 0;
int j = len - 1;
while (i < j)
{
int tmp = arr[i];
arr[i] = arr[j];
arr[j] = tmp;
i++;
j–;
}
for(int i=0;i<len;i++)
{
printf(“%d”, arr[i]);
}
return 0;
}
//给数组输入元素ctrl+d向下复制
int main7()
{
int arr[5];
int len = sizeof(arr) / sizeof(arr[0]);
for (int i = 0;i < len;i++)
{
scanf(“%d”, &arr[i]);
}
printf(“刚才输入的数组是：\n”);
for (int i = 0;i < len;i++)
{
printf(“%d\n”,arr[i ]);
//打印地址
printf(“&arr[%d]为%d\n”,i,&arr[i]);//或用%p打印地址
}
return 0;
}
//1-100能被3整除的数ctrl+k->ctrl+c多行注释 ctrl+k->ctrl+u取消注释
int main6()
{
for (int i = 1;i <= 100;i++)
{
if (i % 3 != 0)
{
continue;
}
printf(“%d\n”,i);
}
return 0;
}
//九九乘法表=======================
int main5()
{
int i,j;
printf(“九九乘法表\n”);
for (i = 1;i <= 9;i++)
{
for (j = 1;j <= i;j++) { printf("%d*%d=%-2d ", j, i, j * i); } printf("\n"); } return 0;}
//求1-100之间2的倍数之和=========================
int main4()
{
int i;
int tmp = 0;
for (i = 1;i <= 100; i++)
{
if (i % 2 == 0)
{
tmp += i;
}
}
printf(“%d”, tmp);
return 0;
}
//求n的阶乘======================================
int main3()
{
int n;
int i=1;
int x=1;
scanf(“%d”, &n);
while (i<=n)
{
x*= i;
i++;
}
printf(“%d”,x);
return 0;
}
//=============================================
int main2()
{
int n;
scanf(“%d”, &n);
while (n != 0)
{
printf("%d ", n % 10);
n=n / 10;
}
return 0;}
//奇偶数=======================================
int main1()
{
int n;
while (scanf(“%d”, &n) != EOF)
{
if (n % 2 != 0)
{
printf(“%d is 奇数\n”, n);
}
else
{
printf(“%d is 偶数\n”, n);
}
}
return 0;
}
