C. Book Reading （Codeforces Round #582 (Div. 3)）

发布时间：2020-12-16 09:15:53 所属栏目：百科来源：网络整理

导读：Polycarp is reading a book consisting of? n n?pages numbered from? 1 1?to? n n. Every time he finishes the page with the number divisible by? m m,he writes down the last digit of this page number. For example,if? n = 15 n=15?and? m = 5 m=5

Polycarp is reading a book consisting of?

Your task is to calculate the sum of all digits Polycarp has written down.

You have to answer?

Input

The first line of the input contains one integer?

The following?

Output

For each query print the answer for it — the sum of digits written down by Polycarp.

Example

input

Copy

7
1 1
10 1
100 3
1024 14
998244353 1337
123 144
1234312817382646 13

output

Copy

1
45
153
294
3359835
0
427262129093995

分析：计算出n范围内m的个位数的倍数的个位数的和

#include <bits/stdc++.h>
 
#define TOP 10001
 
using namespace std; typedef long long ll; int main() { ios_base::sync_with_stdio(0); cin.tie(0); map<int,vector<int> > r; int q; ll m,n,coc,rest,fin,ans; vector<int> aux; r[1] = {1,2,3,4,5,6,7,8,9,0}; r[2] = {2,0}; r[3] = {3,1,0}; r[4] = {4,0}; r[5] = {5,0}; r[6] = {6,0}; r[7] = {7,0}; r[8] = {8,0}; r[9] = {9,0}; cin >> q; while(q--){ cin >> n >> m; coc = n / m; fin = m % 10; ans = 0; if(fin != 0){ aux = r[fin]; n = aux.size(); rest = coc % n; coc /= n; for(int i = 0; i < n; ++i) ans += aux[i] * (coc + (i < rest)); } cout << ans << ‘n‘; } return 0; }

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!