Java/src/dp/mcm/ScrambledStringProblem.java at master · kasodeep/Java · GitHub

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package dp.mcm;

import java.util.HashMap;

public class ScrambledStringProblem {

    static HashMap<String, Boolean> mp = new HashMap<>();

    static boolean isScramble(String s1, String s2) {
        int n = s1.length();
        boolean flag = false, swap, noSwap;

        if (s1.equals(s2)) return true;
        if (s1.length() <= 1) return false;

        String key = s1 + "_" + s2;
        if (mp.containsKey(key)) return mp.get(key);

        for (int i = 1; i < n; i++) {
            noSwap = (isScramble(s1.substring(0, i), s2.substring(0, i)) &&
                    isScramble(s1.substring(i, n), s2.substring(i, n)));

            swap = (isScramble(s1.substring(0, i), s2.substring(n - i, n)) &&
                    isScramble(s1.substring(i, n), s2.substring(0, n - i)));

            if (swap || noSwap) {
                flag = true;
                break;
            }
        }
        mp.put(key, flag);
        return flag;
    }
}