几个比较好的countdown js
Problem B
Super Number
Input: Standard Input
Output: Standard Output
Time Limit: 3 Seconds
Don‘t you think 162456723 very special? Look at the picture below if you are unable to find its speciality. (a | b means ‘b is divisible by a’)
Figure: Super Numbers
Given n, m (0 < n < m < 30), you are to find a m-digit positive integer X such that for every i (n <= i <= m), the first i digits of X is a multiple ofi. If more than one such X exists, you should output the lexicographically smallest one. Note that the first digit of X should not be 0.
Input
Output
For each test case, print the case number and X. If no such number, print -1.
Sample Input Output for Sample Input
2 1 10 3 29 |
Case 1: 1020005640 Case 2: -1
|
Problemsetter: Rujia Liu, Member of Elite Problemsetters‘ Panel
Special Thanks to:
Monirul Hasan (Alternate solution)
Shahriar Manzoor (Figure Drawing)
题意:给定两个数字n,m;求一个长度为m的数字使得这个数字的任意前i(n=<i<=m)个数字组成的数能被i整数。
这道题按照我的思路就是回溯暴力。暂时没想到更好的方法了。
#include<iostream> #include<cstring> using namespace std; int n,m,tag; int arry[50]; int mod(int cnt) { int sum=0; for(int i=0;i<cnt;i++) { sum=(sum*10+arry[i])%cnt; } return sum; } void dfs(int pos) { if(pos==m) { tag=1; return; } if(tag) return; for(int i=0;i<=9;i++) { arry[pos]=i; if(pos<n-1||(pos>=n-1&&!mod(pos+1))) { dfs(pos+1); if(tag) return; } } } int main() { int k; cin>>k; for(int t=1;t<=k;t++) { tag=0; cin>>n>>m; memset(arry,0,sizeof(arry)); int i,j; for(i=1;i<=9;i++) { arry[0]=i; dfs(1); if(tag) break; } cout<<"Case "<<t<<": "; if(tag) { for(i=0;i<m;i++) cout<<arry[i]; } else cout<<"-1"; cout<<endl; } return 0; }
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