Java Program For Longest Common Substring

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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class JavaCommonSubstring {

	public static void main(String[] args) throws IOException {
		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		System.out.println("Enter String 1: ");
		String s1 = br.readLine();
		System.out.println("Enter String 2: ");
		String s2 = br.readLine();
		printLongestCommonSubstring(s1, s2);
		br.close();
	}

	private static void printLongestCommonSubstring(String s1, String s2) {
		int m = s1.length();
		int n = s2.length();

		int max = 0;
		int pos = 0;

		int[][] array = new int[m][n];

		for (int i = 0; i < m; i++) {
			for (int j = 0; j < n; j++) {
				if (s1.charAt(i) == s2.charAt(j)) {
					if (i == 0 || j == 0) {
						array[i][j] = 1;
					} else {
						array[i][j] = array[i - 1][j - 1] + 1;
					}
					if (max < array[i][j]) {
						max = array[i][j];
						pos = i + 1;
					}
				}
			}
		}
		if (pos > 0) {
			System.out.println("Longest common substring between \"" + s1 + "\"" + " and \"" + s2 + "\" is: "
					+ s1.substring(pos - max, pos));
		} else {
			System.out.println("There is no common substring between \"" + s1 + "\" and \"" + s2 + "\"");
		}
	}
}

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