CommonChild.java

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class CommonChild {

    // Complete the commonChild function below.
    static int commonChild(String s1, String s2) {
        int dp[][] = new int[s1.length()+1][s2.length()+1];
        for(int i=0;i<=s1.length();i++){
            for(int j=0;j<=s2.length();j++){
                if(j == 0 || i == 0){
                    dp[i][j] = 0;
                }else if(s1.charAt(i-1) == s2.charAt(j-1)){
                    dp[i][j] = dp[i-1][j-1] + 1;
                }else{
                    dp[i][j] = Math.max(dp[i-1][j], dp[i][j-1]);
                }
            }
        }
        return dp[s1.length()][s2.length()];
        
    }

    private static final Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) throws IOException {
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        String s1 = scanner.nextLine();

        String s2 = scanner.nextLine();

        int result = commonChild(s1, s2);

        bufferedWriter.write(String.valueOf(result));
        bufferedWriter.newLine();

        bufferedWriter.close();

        scanner.close();
    }
}