Educational Codeforces Round 80 (Rated for Div. 2)B. Yet Another Meme Problem（数论）（公式推导）

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最新推荐文章于 2025-06-02 13:01:50 发布

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分类专栏：数论公式推导文章标签： c++

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题目地址:https://codeforces.com/contest/1288/problem/B
大佬地址:https://www.cnblogs.com/yanying7/p/12357953.html
公式推导，数论强者恐怖如斯啊

#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cmath>
#include<string>
#include<iostream>
#include<algorithm>
#include<map>
#include<set>
#include<stack>
#include<queue>
#include<vector>
#define ll long long
#define dd double
#define PI acos(-1.0)
#define f(i, x, y) for(ll i = x; i < y; i++)
using namespace std;
const ll MAXN = 2e5 + 5;
int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	ll n; cin >> n;
	f(i, 0, n) {
		ll n, d;
		cin >> n >> d;
		ll cnt = 0;
		ll t = 9;
		while (t <= d) {
			cnt++;
			t = t * 10 + 9;
		}
		cout << n * cnt << endl;
	}
	
}