Optimized C ++ program for n 'th perrin number
#include <bits/stdc++.h> NEW_LINE using namespace std ; int per ( int n ) { int a = 3 , b = 0 , c = 2 , i ; int m ; if ( n == 0 ) return a ; if ( n == 1 ) return b ; if ( n == 2 ) return c ; while ( n > 2 ) { m = a + b ; a = b ; b = c ; c = m ; n -- ; } return m ; }