C++ 代码：
#include
using namespace std;
int n, num[10005];
void work(){
int cnt, i, tmp;
num[0] = 0;
for(i=1; i<=10000; i++){
cnt = 0; tmp = i;
while(tmp){
if(tmp%10 == 1){cnt++; }
tmp/=10;
}
num[i] = num[i-1] + cnt;
}
}
int main(){
int i,ans;
work();
cin>>i;
cout< return 0;
}
