Longest subsequence with a given AND value | C ++ implementation of the approach ; To store the states of DP ; Function to return the required length ; Base case ; If the state has been solved before return the value of the state ; Setting the state as solved ; Recurrence relation ; Driver code
#include <bits/stdc++.h> NEW_LINE using namespace std ; #define maxN  20 NEW_LINE #define maxM  64 NEW_LINE int dp [ maxN ] [ maxM ] ; bool v [ maxN ] [ maxM ] ; int findLen ( int * arr , int i , int curr , int n , int m ) { if ( i == n ) { if ( curr == m ) return 0 ; else return -1 ; } if ( v [ i ] [ curr ] ) return dp [ i ] [ curr ] ; v [ i ] [ curr ] = 1 ; int l = findLen ( arr , i + 1 , curr , n , m ) ; int r = findLen ( arr , i + 1 , curr & arr [ i ] , n , m ) ; dp [ i ] [ curr ] = l ; if ( r != -1 ) dp [ i ] [ curr ] = max ( dp [ i ] [ curr ] , r + 1 ) ; return dp [ i ] [ curr ] ; } int main ( ) { int arr [ ] = { 3 , 7 , 2 , 3 } ; int n = sizeof ( arr ) / sizeof ( int ) ; int m = 3 ; int ans = findLen ( arr , 0 , ( ( 1 << 8 ) - 1 ) , n , m ) ; if ( ans == -1 ) cout << 0 ; else cout << ans ; return 0 ; }