B - Least Common Multiple
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
題意:給你n個數,求他們的最小公倍數
思路:首先有一個定理:兩個數的乘積等於最大公因數與最小公倍數的乘積,所以我們可以先求最大公因數(gcd法)
#include<stdio.h> int gcd(int n,int m) { int t,ans; int a = n,b = m; if(n < m) //gcd要求分子要最大 { t = n; n = m; m = t; } while(m) { ans = m; m = n%m; n = ans; } return a/n*b; //防止兩數乘積過大 } int main() { int t,n,i,m; long long ans = 1; scanf("%d",&t); while(t--) { scanf("%d",&n); ans = 1; for(i = 0;i < n;++i) { scanf("%d",&m); ans=gcd(ans,m); } printf("%lld\n",ans); } }