function that returns ( n + 1 ) th Fibonacci number Or number of ways to represent n as sum of 1 ' s ▁ ▁ 2' s
static int countWays ( int n ) { int [ , ] F = { { 1 , 1 } , { 1 , 0 } } ; if ( n == 0 ) { return 0 ; } power ( F , n ) ; return F [ 0 , 0 ] ; }