codeforces-894C Marco and GCD Sequence
来源:互联网 发布:js奇偶数判断的代码 编辑:程序博客网 时间:2024/05/21 17:28
C. Marco and GCD Sequence
time limit per test1 secondmemory limit per test256 megabytes
inputstandard input
outputstandard output
In a dream Marco met an elderly man with a pair of black glasses. The man told him the key to immortality and then disappeared with the wind of time.
When he woke up, he only rem embered that the key was a sequence of positive integers of some length n, but forgot the exact sequence. Let the elements of the sequence be a1, a2, ..., an. He remembered that he calculated gcd(ai, ai + 1, ..., aj) for every 1 ≤ i ≤ j ≤ n and put it into a set S. gcd here means the greatest common divisor.
Note that even if a number is put into the set S twice or more, it only appears once in the set.
Now Marco gives you the set S and asks you to help him figure out the initial sequence. If there are many solutions, print any of them. It is also possible that there are no sequences that produce the set S, in this case print -1.
Input
The first line contains a single integer m (1 ≤ m ≤ 1000) — the size of the set S.
The second line contains m integers s1, s2, ..., sm (1 ≤ si ≤ 106) — the elements of the set S. It's guaranteed that the elements of the set are given in strictly increasing order, that means s1 < s2 < ... < sm.
Output
If there is no solution, print a single line containing -1.
Otherwise, in the first line print a single integer n denoting the length of the sequence, n should not exceed 4000.
In the second line print n integers a1, a2, ..., an (1 ≤ ai ≤ 106) — the sequence.
We can show that if a solution exists, then there is a solution with n not exceeding 4000 and ai not exceeding 106.
If there are multiple solutions, print any of them.
Examples
input
4
2 4 6 12
output
3
4 6 12
input
2
2 3
output
-1
Note
In the first example 2 = gcd(4, 6), the other elements from the set appear in the sequence, and we can show that there are no values different from 2, 4, 6 and 12 among gcd(ai, ai + 1, ..., aj) for every 1 ≤ i ≤ j ≤ n.
题意:一个序列是求出原来的任意两个数(i<j)的gcd(a[i],a[j]),如果gcd不在序列中就把它放进去。求原来的序列,会有多个答案。
思路:任意两个数的gcd,最小的肯定会放在第一个,如果第一个不能被整除的话,结果就是-1。如果是的话,就把第一个数放入序列中
#include<stdio.h>#include<string>#include<iostream>#include<math.h>#define ll long long#define maxn 1003using namespace std;int a[maxn];int main(){ int n; cin>>n; cin>>a[0]; for(int i=1;i<n;i++) { cin>>a[i]; if(a[i]%a[0]!=0) { cout<<-1<<endl;return 0; } } cout<<2*n-1<<endl; for(int i=0;i<n-1;i++) { cout<<a[i]<<" "<<a[0]<<" "; } cout<<a[n-1]<<endl;}
阅读全文
0 0
- codeforces-894C Marco and GCD Sequence
- codeforces 864C Marco and GCD Sequence
- codeforces C. Marco and GCD Sequence
- Codeforces 894C C. Marco and GCD Sequence
- Codeforces 894C:Marco and GCD Sequence(构造)
- Codeforces Round #447 (Div. 2) C. Marco and GCD Sequence
- Codeforces Round #447 (Div. 2) C. Marco and GCD Sequence
- Codeforces Round #447 (Div. 2) C. Marco and GCD Sequence
- Codeforces Round #447 (Div. 2) C. Marco and GCD Sequence
- Marco and GCD Sequence
- Codeforces Round #447 (Div. 2) C. Marco and GCD Sequence 构造
- Codeforces Round #447 (Div. 2) C. Marco and GCD Sequence (构造 贪心)
- Codeforces Round #447 (Div. 2) C. Marco and GCD Sequence(构造,思路)
- Codeforces Round #447 (Div. 2) C. Marco and GCD Sequence(构造)
- Codeforces Round #447 (Div. 2) C. Marco and GCD Sequence 构造
- CF-Marco and GCD Sequence
- Codeforces894C Marco and GCD Sequence
- Codeforces 798C Mike and gcd problem
- java涨姿势--反射知识篇
- 数据结构实验之图论十:判断给定图是否存在合法拓扑序列
- 任意进制转换
- 京东京麦开放平台的高可用架构之路
- EasyDemo*常用API体系结构图(download pic Thx)
- codeforces-894C Marco and GCD Sequence
- 【Scikit-Learn 中文文档】优化估计器的超参数
- Tensorflow CIFAR-10训练例子报错解决
- 朴素贝叶斯分类Naive Bayesian
- Single Number III
- 引入Fresco 网络加载图片的学习
- 【Scikit-Learn 中文文档】模型评估: 量化预测的质量
- 如何快速且准确地运用搜索引擎查找资料
- http请求头详解