Following steps build L [ m + 1 ] [ n + 1 ] in bottom up fashion . Note that L [ i ] [ j ] contains cost of removing identical characters in LCS of X [ 0. . i - 1 ] and Y [ 0. . j - 1 ]
for ( $ i = 0 ; $ i <= $ m ; ++ $ i ) { for ( $ j = 0 ; $ j <= $ n ; $ j ++ ) { if ( $ i == 0 $ j == 0 ) $ L [ $ i ] [ $ j ] = 0 ;