PAT A1049. Counting Ones (30)

The task is simple: given any positive integer N, you are supposed to count the total number of 1's in the decimal form of the integers from 1 to N. For example, given N being 12, there are five 1's in 1, 10, 11, and 12.

Input Specification:

Each input file contains one test case which gives the positive N (<=2³⁰).

Output Specification:

For each test case, PRint the number of 1's in one line.

12Sample Output:
5
#include <cstdio>#include <algorithm>#include <cstring>#include <string>#define Max 100010using namespace std;int main(){	int n,k=1;	int m=0;	int p,q,r,l;	scanf("%d",&n);	for(int i=1;i<=n;i++)	{		p=i;		while(p!=0)		{			q=p%10;			if(q==1) m++;			p=p/10;		}	}		printf("%d/n",m);	system("pause");	return 0;}