LCS ( Longest Common Subsequence ) of three strings | C ++ program to find LCS of three strings ; Returns length of LCS for X [ 0. . m - 1 ] , Y [ 0. . n - 1 ] and Z [ 0. . o - 1 ] ; Following steps build L [ m + 1 ] [ n + 1 ] [ o + 1 ] in bottom up fashion . Note that L [ i ] [ j ] [ k ] contains length of LCS of X [ 0. . i - 1 ] and Y [ 0. . j - 1 ] and Z [ 0. . ... k - 1 ] ; L [ m ] [ n ] [ o ] contains length of LCS for X [ 0. . n - 1 ] and Y [ 0. . m - 1 ] and Z [ 0. . o - 1 ] ; Driver program to test above function
#include <bits/stdc++.h> NEW_LINE using namespace std ; int lcsOf3 ( string X , string Y , string Z , int m , int n , int o ) { int L [ m + 1 ] [ n + 1 ] [ o + 1 ] ; for ( int i = 0 ; i <= m ; i ++ ) { for ( int j = 0 ; j <= n ; j ++ ) { for ( int k = 0 ; k <= o ; k ++ ) { if ( i == 0 j == 0 k == 0 ) L [ i ] [ j ] [ k ] = 0 ; else if ( X [ i - 1 ] == Y [ j - 1 ] && X [ i - 1 ] == Z [ k - 1 ] ) L [ i ] [ j ] [ k ] = L [ i - 1 ] [ j - 1 ] [ k - 1 ] + 1 ; else L [ i ] [ j ] [ k ] = max ( max ( L [ i - 1 ] [ j ] [ k ] , L [ i ] [ j - 1 ] [ k ] ) , L [ i ] [ j ] [ k - 1 ] ) ; } } } return L [ m ] [ n ] [ o ] ; } int main ( ) { string X = " AGGT12" ; string Y = "12TXAYB " ; string Z = "12XBA " ; int m = X . length ( ) ; int n = Y . length ( ) ; int o = Z . length ( ) ; cout << " Length ▁ of ▁ LCS ▁ is ▁ " << lcsOf3 ( X , Y , Z , m , n , o ) ; return 0 ; }