hdu 1212 Least Common Multiple

Problem Description
The least common multiple (LCM) of a set of positive integers is the smallest positive integer which is divisible by all the numbers in the set. For example, the LCM of 5, 7 and 15 is 105.

Input
Input will consist of multiple problem instances. The first line of the input will contain a single integer indicating the number of problem instances. Each instance will consist of a single line of the form m n1 n2 n3 … nm where m is the number of integers in the set and n1 … nm are the integers. All integers will be positive and lie within the range of a 32-bit integer.

Output
For each problem instance, output a single line containing the corresponding LCM. All results will lie in the range of a 32-bit integer.

Sample Input
2
3 5 7 15
6 4 10296 936 1287 792 1

Sample Output
105
10296

题解：

用欧几里德算法即可。lcm=(a*b)/gcd(a,b)，用了C++函数__gcd求解，注意n==1的特殊情况。

代码：

#include <bits/stdc++.h>using namespace std;int main(){    int T;    cin>>T;    long long tmp;    long long n,x;    long long lcm;    while(T--)    {      cin>>n>>x;      if(n==1) {cout<<x<<endl;continue;}      for(int i=1;i<n;i++)      {          cin>>tmp;          lcm=x*tmp/(__gcd(x,tmp));          x=lcm;      }      cout<<lcm<<endl;    }    return 0;}