[c++] 3의 개수구하기(large)

• 3의 개수구하기

#include<stdio.h>
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
int main() {
	//freopen("input.txt", "rt", stdin);
	int n, cur, k=1, lt=1, rt, res=0;
	scanf("%d", &n);
	while(lt!=0){
		lt=n/(k*10);
		rt=n%k;
		cur=(n/k)%10;
		
		if(cur>3) res=res+((lt+1)*k);
		else if(cur==3) res=res+((lt*k)+(rt+1));
		else res=res+(lt*k);
		
		k=k*10;
	}
	printf("%d\n", res);
	return 0;
}