text: 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
code: function findWaysToPair ( p ) { var dp = Array ( p + 1 ) ; dp [ 1 ] = 1 ; dp [ 2 ] = 2 ; for ( var i = 3 ; i <= p ; i ++ ) { dp [ i ] = dp [ i - 1 ] + ( i - 1 ) * dp [ i - 2 ] ; } return dp [ p ] ; } var p = 3 ; document . write ( findWaysToPair ( p ) ) ;