1049 Counting Ones (30 分)

1049 Counting Ones (30 分)

思路有空更新

#include <iostream>
using namespace std;
int main(){
	int n, wei = 1, now, left, right, ans = 0;
	cin >> n;
	while(n / wei){
		now = n / wei % 10;    //此时位上数字 
		left = n / (wei * 10); //左边数字
		right = n % wei;       //右边数字
		if(now == 0)
			ans += left * wei;
		else if(now == 1)
			ans += left * wei + right + 1;
		else
			ans += (left + 1) * wei;
		wei *= 10;
	}
	cout << ans;
}