2232: [NOIP2013] counting problem T1

Let's come to the simple question today Counting problem T1

topic description

Try to count how many times the number x (0≤x≤9) appears in all the integers in the interval 1 to n? For example, in 1 to 11, that is, in 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, the number 1 occurs 4 times.

enter

Input a total of 1 line, including 2 integers n and x, separated by a space.

output

Output a total of 1 line, containing an integer, indicating the number of occurrences of x.

sample input

11 1

sample output

4

hint

For 100% of the data, 1≤n≤1,000,000, 0≤x≤9

All I can say is, it's easy

This can be regarded as a water problem of NOIP, it is the first time I see that the problem of NOIP is so simple

Talk about ideas:

Traverse the loop, traverse from 1 to n, and then store a temporary value tmp similar to digital division. If tmp%10 == x, that is to say, one bit in tmp is x, store a variable sum, sum++, and finally Just output the sum, it's very simple

upper code

#include <stdio.h>
int main()
{
    int n,x,sum=0;
    scanf("%d %d",&n,&x);
    for(int i=1;i<=n;i++)
    {
        int tmp=i;
        while(tmp>0){
            if(tmp%10==x) sum++;
            tmp/=10;
        }
    }    
    printf("%d",sum);
    return 0;
}

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