Probability of reaching a point with 2 or 3 steps at a time | Returns probability to reach N ; Driver code
< ? php function find_prob ( $ N , $ P ) { $ dp ; $ dp [ 0 ] = 1 ; $ dp [ 1 ] = 0 ; $ dp [ 2 ] = $ P ; $ dp [ 3 ] = 1 - $ P ; for ( $ i = 4 ; $ i <= $ N ; ++ $ i ) $ dp [ $ i ] = ( $ P ) * $ dp [ $ i - 2 ] + ( 1 - $ P ) * $ dp [ $ i - 3 ] ; return $ dp [ $ N ] ; } $ n = 5 ; $ p = 0.2 ; echo find_prob ( $ n , $ p ) ; ? >