Statistics

Question Description:
Input:
k = 1, n = 1
Output:
1
Explanation:
In [0, 1], we find that 1 appears 1 time (1).
Input:
k = 1, n = 12
Output:
5
Explanation:
In [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12], we find that 1 appears 5 times (1, 10, 11, 12) (note that there are two 1s in 11).

Analysis: When k=0, 0 starts to be one more than other numbers less than or equal to 10.

Code:

#include<iostream>
using namespace std;
int f(int ,int );
int main()
{
    
    
	int i;
	i=f(0,29);
	cout<<i<<endl;
	
 } 
 
 int f(int k,int n)
 {
    
    
 	int count ;//作为返回值  
	if(k==0)
	count=1;
	
	for(int i=0;i<=n;i++) 
	{
    
    
		int m=i; 
		while(m)
		{
    
    
			if(m%10==k)
			{
    
    
				count++;
			}
			m/=10;
		}
	}
		return count;
 }