Longest Common Subsequence | DP | Dynamic Programming C # implementation of LCS problem ; find the length of the strings ; Following steps build L [ m + 1 ] [ n + 1 ] in bottom up fashion . Note : L [ i ] [ j ] contains length of LCS of X [ 0. . i - 1 ] and Y [ 0. . j - 1 ] ; L [ m ] [ n ] contains the length of LCS of X [ 0. . n - 1 ] & Y [ 0. . m - 1 ] ; Driver Code
< ? php function lcs ( $ X , $ Y ) { $ m = strlen ( $ X ) ; $ n = strlen ( $ Y ) ; for ( $ i = 0 ; $ i <= $ m ; $ i ++ ) { for ( $ j = 0 ; $ j <= $ n ; $ j ++ ) { if ( $ i == 0 $ j == 0 ) $ L [ $ i ] [ $ j ] = 0 ; else if ( $ X [ $ i - 1 ] == $ Y [ $ j - 1 ] ) $ L [ $ i ] [ $ j ] = $ L [ $ i - 1 ] [ $ j - 1 ] + 1 ; else $ L [ $ i ] [ $ j ] = max ( $ L [ $ i - 1 ] [ $ j ] , $ L [ $ i ] [ $ j - 1 ] ) ; } } return $ L [ $ m ] [ $ n ] ; } $ X = " AGGTAB " ; $ Y = " GXTXAYB " ; echo " Length ▁ of ▁ LCS ▁ is ▁ " ; echo lcs ( $ X , $ Y ) ; ? >