c++ - Calculate LCM of N numbers modulo 1000000007 -

i solving following problem on lcm : calculate lcm of n numbers modulo 1000000007

my approach :

typedef unsigned long long ull; const ull mod=1000000007; ull a[10009]; /*euclidean gcd*/ ull gcd(ull a,ull b) {     while( b != 0)     {         ull  t = b;         b= %t;         = t;     }     return a; } ull lcm(ull a, ull b)  {      return (a/gcd(a,b))%mod*(b%mod);  } ull lcms(int  l ,ull * a) {     int     i;     ull result;     result = 1;     (i = 0; < l; i++)          result = lcm(result, a[i])%1000000007;     return result; } int main() {     int t;     cin>>t;     while(t--)/*number of test cases*/     {         int n;         cin>>n;/*how many numbers in array*/         for(int i=0;i<n;++i)         {             cin>>a[i];//input array         }         cout<<lcms(n,a)%1000000007<<endl;     }     return 0; } 

i getting wrong answer when submit solution. constraints are:

1<=n<=1000 , 1<=a[i]<=10000 

at ideone

i guess getting wrong answer because of overflow. how can improve code?

thanks!

1000000007 big me take example. let me use 17 example:

lcms(10, 9, 8) % 17 = lcm(10, lcm(9, 8)) % 17 = lcm(10, 72) % 17 = 360 % 17 = 3 

this code doing:

lcms(10, 9, 8) % 17 = lcm(10, lcm(9, 8) % 17) % 17 = lcm(10, 72 % 17) % 17 = lcm(10, 4) % 17 = 40 % 17 = 6 

which wrong.

also @ ideone