LongestCommonSubsequence.java

// Finding Longest Common Subsequence of Two Strings Using Dynamic Programming
import java.util.Scanner;

public class LongestCommonSubsequence {
	int lcs(char[] X, char[] Y, int m, int n) {
		int DP[][] = new int[m + 1][n + 1];
		// Bottom-Up Approach for dp
		for (int i = 0; i <= m; i++) {
			for (int j = 0; j <= n; j++) {
				if (i == 0 || j == 0)
					DP[i][j] = 0;
				else if (X[i - 1] == Y[j - 1])
					DP[i][j] = DP[i - 1][j - 1] + 1;
				else
					DP[i][j] = max(DP[i - 1][j], DP[i][j - 1]);
			}
		}
		return DP[m][n];
	}

	int max(int a, int b) {
		if (a > b)
			return a;
		else
			return b;
	}

	public static void main(String[] args) {
		LongestCommonSubsequence obj = new LongestCommonSubsequence();
		String s1 = "", s2 = "";
		Scanner scan = new Scanner(System.in);
		System.out.println("Enter 1st String");
		s1 = scan.next();
		System.out.println("Enter 2nd String");
		s2 = scan.next();
		char[] X = s1.toCharArray();
		char[] Y = s2.toCharArray();
		int m = X.length;
		int n = Y.length;
		System.out.println("Length of Longest Common Subsequence is: " + obj.lcs(X, Y, m, n));
	}
}