Preliminary level of C language -- selected good questions on niuke.com

BC68 X Shape patterns

describe

KiKi I learned the cycle ,BoBo The teacher gave him a series of printing exercises , The task is to print “*” Composed of X Shape patterns .

Input description ：

Multi group input , An integer （2~20）, Represents the number of rows output , It also means composition “X” The length of the backslash and the backslash of .

Output description ：

Enter... For each line , For output “*” Composed of X Shape patterns .

#define _CRT_SECURE_NO_WARNINGS 1 // Make sure scanf Functions can all be vs Use... Under compiler 
#include <stdio.h>
int main()
{
    
    char arr[20][20] = {
     0 };       // Create a 2D array 
    int i = 0;
    int j = 0;
    int a = 0;
    while (scanf("%d", &a)!=EOF)     // Use loops to implement multiple sets of inputs 
    {
    
       
        for (i = 0;i < 20;i++)     // Initialize all array elements to spaces 
        {
    
            for (j = 0;j < 20;j++)
            {
    
                arr[i][j] = ' ';
            }
        }

        for (i = 0, j = 0;i < a, j < a;i++, j++)     // The positive diagonal element is changed to ‘*’
        {
    
            arr[i][j] = '*';
        }
        for (i = 0, j = a - 1;i < a, j >= 0;i++, j--) // The anti diagonal element is changed to ‘*’
        {
    
            arr[i][j] = '*';
        }
        for (i = 0;i < a;i++)     // Print out elements 
        {
    
            for (j = 0;j < a;j++)
            {
    
                printf("%c", arr[i][j]);
            }
            printf("\n");
        }
    }
    return 0;
}

BC54 Get the number of days in the month

describe

KiKi Want to get how many days there are in a certain month in a certain year , Please program it for him . Enter the year and month , Calculate the number of days in this month of the year .

Input description ：

Multi group input , There are two integers in a row , Represents year and month respectively , Separate... With spaces .

Output description ：

Enter... For each group , Output as a line , An integer , It means how many days there are in this month of the year .

#define _CRT_SECURE_NO_WARNINGS 1 // Make sure scanf Functions can all be vs Use... Under compiler 
#include <stdio.h>
int is_leap_yeay(int x)        //  Determine whether the year is a leap year 
{
    
	if (((x % 4 == 0) && (x % 100 != 0)) || x % 400 == 0)
		return 29;
	else 
		return 28;
}
int main()
{
    
	int year = 0;
	int month = 0;
	int a = 0;
	while (scanf("%d%d", &year, &month)!=EOF)
	{
    
		if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12)          //  Big moon is 31 God 
		{
    
			printf("31\n");
		}
		else if (month == 2)     //2 Month is a special month , Call the function to determine whether it is a leap year 
		{
    
			int a = is_leap_yeay(year);
			printf("%d\n", a);
		}
		else       // Other cases are Xiaoyue 30 God 
		{
    
			printf("30\n");
		}
	}
		return 0;
}

BC51 Triangle judgment

describe

KiKi Want to know the three sides that have been given a,b,c Can it form a triangle , If you can form a triangle , Judge the type of triangle （ Equilateral triangle 、 Isosceles triangle or ordinary triangle ）.

Input description ：

The title has multiple sets of input data , Enter three... On each line a,b,c(0<a,b,c<1000), As the three sides of a triangle , Separate... With spaces .

Output description ：

Enter data for each group , Output takes up one line , If you can form a triangle , Equilateral triangles output “Equilateral triangle!”, Isosceles triangle outputs “Isosceles triangle!”, The rest of the triangles are output “Ordinary triangle!”, On the contrary, output “Not a triangle!”.

#define _CRT_SECURE_NO_WARNINGS 1 // Make sure scanf Functions can all be vs Use... Under compiler 
#include <stdio.h>
int main()
{
    
	int a = 0;
	int b = 0;
	int c = 0;
	while (scanf("%d%d%d", &a, &b, &c)!=EOF)
	{
    
		if ((a + b > c) && (a + c > b) && (b + c > a))         // Judge whether it is a triangle 
		{
    
			if ((a == b && b!=c )|| (b == c && c!=a)|| a == c && c!=b)       // Judge whether it is an isosceles triangle 
			{
    
				printf("Isosceles triangle!\n");
			}
			else if (a == b && b == c && c == a)          // Judge whether it is an equilateral triangle 
			{
    
				printf("Equilateral triangle!\n");
			}
			else
			{
    
				printf("Ordinary triangle!\n");
			}
		}
		else
		{
    
			printf("Not a triangle!");
		}
	}
	return 0;
}