Niuke net question brushing training (I)

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Preface

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1.printf Return value

describe
KiKi Write an output “Hello world!” The program ,BoBo The teacher told him printf Function has return value , You can write him a program output printf(“Hello world!”) Return value of ？

Input description ：
nothing

Output description ：
It includes two lines ：
First act “Hello world!”
Second behavior printf(“Hello world!”) The return value after the call .

#include<stdio.h>
int main()
{
    
    printf("\n%d",printf("Hello world!"));
    return 0;
}

The problem seems simple But it is not Need to know printf The return value of the function is the number of printed characters
First, the output Hello world！
Hello world! share 12 individual
printf（“%d",12);
Because the title requires two lines of output So in %d prefix \n

2. Civil service interview

describe
Civil servant interview on-site scoring . Yes 7 Examiner , Enter several groups of grades from the keyboard , Each group 7 A score （ Percentage system ）, Take out the highest score and the lowest score , Output the average score of each group .
（ notes ： There are many groups of input ）
Input description ：
Every line , Input 7 It's an integer （0~100）, representative 7 Achievements , Separate... With spaces .
Output description ：
Every line , Output the average score excluding the highest and lowest scores , After the decimal point 2 position , Wrap after output of each line .

Example 1
Input ：
99 45 78 67 72 88 60
Output ：
73.00

#include<stdio.h>
int main()
{
    
    int i=0;
    int s=0;
    int max=0;
    int min=100;
    int sum=0;
    int count=0;
    while(scanf("%d",&s)!=EOF)
    {
    
        count++;
        sum=sum+s;
        if(s>max)
        {
    
            max=s;
        }
        if(s<min)
        {
    
            min=s;
        }
        if(count==7)
        {
    
            printf("%.2f\n",(sum-max-min)/5.0);
            count=0;
            sum=0;
            max=0;
            min=100;
        } 
    }
    return 0;
}

A problem that must be paid attention to in this problem is :（ notes ： There are many groups of input ）
So we have to adopt while loop The way
Used here count To calculate the number of points passed
Be equal to 7 Output when , And set the maximum value minimum value Record the total quantity count count Should be restored to the original value
When outputting, you should also pay attention to Divide two integers Will round off the decimal So add .0 Convert it to decimal

3. Character Christmas tree

describe
Enter a character , Use it to construct a side length of 5 A triangular Christmas tree .
Data range ： Ensure that the input character is a char Type value

Input description ：
There is only one line of input , A character .
Output description ：
This character forms a triangular Christmas tree .

#include<stdio.h>
int main()
{
    
    int N=0;
    scanf("%c",&N);
    int i=0;
    int j=0;
    for(i=0;i<5;i++)
    {
    
            for(j=0;j<5-1-i;j++)
            {
    
                printf(" ");
            }
            for(j=0;j<=i;j++)
            {
    
                printf("%c ",N);
            }
        printf("\n");
    }
    return 0;
}

This problem is divided into several parts
First of all, we need to Build to build a triangle Based on side length 5 example
1
1 1
1 1 1
1 1 1 1
1 1 1 1 1
2： We will find that The difference with the requirements of the topic is only on the blank
The first row is only inferior to the leftmost row 4 A space —N-1
The second row is only inferior to the leftmost row 3 A space —N-2
That is to say N-1-i A space

4. Insert a number in an ordered sequence

describe
There is an ordered sequence of numbers , Sort from small to large , Insert a newly entered number into the sequence , Ensure that after inserting a new number , The sequence is still in ascending order .

Input description ：
Enter an integer in the first line (0≤N≤50).
Second line input N An integer in ascending order , Enter space delimited N It's an integer .
On the third line, enter an integer you want to insert .
Output description ：
Output as a line ,N+1 An ordered integer .

Input ：
5
1 6 9 22 30
8
Output ：
1 6 8 9 22 30

#include<stdio.h>
int main()
{
    
    int N=0;
    scanf("%d",&N);
    int arr[40]={
    0};
    int i=0;
    for(i=0;i<N;i++)
    {
    
        scanf("%d",&arr[i]);
    }
    int tmp=0;
    scanf("%d",&tmp);
    for(i=N-1;i>=0;i--)
    {
    
        if(arr[i]>tmp)
        {
    
            arr[i+1]=arr[i];
        }
        else
        {
    
            arr[i+1]=tmp;
            break;
        }
    }
    if(i==-1)
    {
    
        arr[0]=tmp;
    }
    for(i=0;i<=N;i++)
    {
    
        printf("%d ",arr[i]);
    }
    return 0;
}

The main idea of this question is Compare the inserted numbers from back to front
If the number in the array is larger than the number inserted Then assign the number in the array backward
If the number in the array is smaller than the number inserted Then put the inserted number in the last digit of the current array
for example ：

If 8 Less than 30 30 Pass back Move the array forward one bit
If 8 Greater than 6 Will 8 Insert 6 The last one of them

5.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 .

#include<stdio.h>
int main()
{
    
    int i=0;
    int j=0;
    int N=0;
    while(scanf("%d",&N)!=EOF)
    {
    
        for(i=0;i<N;i++)
        {
    
           for(j=0;j<N;j++)
           {
    
               if(i==j||i+j==N-1)
               {
    
                   printf("*");
               }
               else
               {
    
                   printf(" ");
               }
           }
            printf("\n");
        }
    }
    return 0;
}

If you want to understand this problem Will know How did it come
First, we regard it as a square
List subscripts in order
This is what we found that the left underline is good i== j That is to say Rows are equal to columns
The right underline is i+j ==N-1 The addition of rows and columns is any minus 1
Other assignments are blank

summary

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