Count of groups among N people having only one leader in each group | Java program for the above approach ; Function to find 2 ^ x using modular exponentiation ; Base cases ; If B is even ; If B is odd ; Function to count the number of ways to form the group having one leader ; Find 2 ^ ( N - 1 ) using modular exponentiation ; Count total ways ; Print the total ways ; Driver Code ; Given N number of peoples ; Function Call
import java . util . * ; class GFG { static long mod = 1000000007 ; static int exponentMod ( int A , int B ) { if ( A == 0 ) return 0 ; if ( B == 0 ) return 1 ; long y ; if ( B % 2 == 0 ) { y = exponentMod ( A , B / 2 ) ; y = ( y * y ) % mod ; } else { y = A % mod ; y = ( y * exponentMod ( A , B - 1 ) % mod ) % mod ; } return ( int ) ( ( y + mod ) % mod ) ; } static void countWays ( int N ) { long select = exponentMod ( 2 , N - 1 ) ; long ways = ( ( N % mod ) * ( select % mod ) ) ; ways %= mod ; System . out . print ( ways ) ; } public static void main ( String [ ] args ) { int N = 5 ; countWays ( N ) ; } }