SerSeries GP | Coding Problem

Problem Statement

Given the A and R i,e first term and common ratio of a GP series. Find the Nth term of the series.

Example 1:

Input: A = 2, R = 2, N = 4
Output: 16
Explanation: The GP series is 
2, 4, 8, 16, 32,... in which 16 
is th 4th term.

problem solving

Example 2:

Input: A = 4, R = 3, N = 3
Output: 36
Explanation: The GP series is
4, 12, 36, 72,.. in which 36 is
the 3rd term.

Expected Time Complexity: O( LogN)
Expected Space Complexity: O(1)

Constraints:
1 <= A, R, N <= 1000000

Code & Algorithm:

/* author : @akash */
/* 
c++ code
*/
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define pb push_back
#define mod 1000000007
#define ld long double
void solve()
{
  int a;
  int R;
  cin>>a>>R;
  int n;
  cin>>n;
  cout<<a*pow(R,n-1);
}
int main()
{
 ios_base::sync_with_stdio(0);
 cin.tie(0);
 cout.tie(0);
 int t;
 cin>>t;
 while(t--)
 {
            solve();
            cout<<"\n";     
 }
 return 0;
}
// time complexity of this algorithm is : T(n)=O(LogN)

Thank You.

Akash Kumar

Software Engineer