Number of ways to pair people | Function to find number of ways to pair people in party ; To store count of number of ways . ; Using the recurrence defined find count for different values of p . ; Driver code
< ? php function findWaysToPair ( $ p ) { $ dp = array ( ) ; $ dp [ 1 ] = 1 ; $ dp [ 2 ] = 2 ; for ( $ i = 3 ; $ i <= $ p ; $ i ++ ) { $ dp [ $ i ] = $ dp [ $ i - 1 ] + ( $ i - 1 ) * $ dp [ $ i - 2 ] ; } return $ dp [ $ p ] ; } $ p = 3 ; echo findWaysToPair ( $ p ) ; ? >