(UVA) String to Palindrome - Solution 1

Link to the problem: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=24&page=show_problem&problem=1680

The solution below used Dynamic Programming to solve this problem.


import java.io.*;
import java.util.*;

class Main {
    public String s;
    public int[][] memo;
   
    public int rec(int left, int right) {
        if (left >= right) {
            return 0;
        }
       
        if (memo[left][right] != -1) {
            return memo[left][right];
        }

        int min = Integer.MAX_VALUE;
        min = Math.min(min, rec(left, right-1) + 1); // insert left
        min = Math.min(min, rec(left+1, right) + 1); // delete left
        min = Math.min(min, rec(left+1, right-1) + ((s.charAt(left) == s.charAt(right)) ? 0 : 1)); // replace
       
        memo[left][right] = min;
        return memo[left][right];
    }
   
    public void process() throws NumberFormatException, IOException {
        Scanner sc = new Scanner(System.in);
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int numTests = sc.nextInt();
        memo = new int[1024][1024];
        for (int test = 0; test < numTests; test++) {
            s = sc.next();

            for (int i = 0; i < s.length(); i++) {
                for (int j = 0; j < s.length(); j++) {
                    memo[i][j] = -1;
                }
            }
           
            bw.write("Case " + (test+1) + ": ");
            bw.write(rec(0, s.length()-1)+"\n");
        }
                                              
        bw.flush();
        bw.close();
       
        return;
    }
   
    public static void main(String[] args) throws NumberFormatException, IOException {
        Main m = new Main();
        m.process();
       
        System.exit(0);
    }
}