_838.java

package com.fishercoder.solutions.firstthousand;

import java.util.HashSet;
import java.util.Set;

public class _838 {
    public static class Solution1 {
        public String pushDominoes(String dominoes) {
            StringBuilder currentSb = new StringBuilder(dominoes);
            Set<String> visited = new HashSet<>();
            visited.add(dominoes);
            do {
                StringBuilder newSb = new StringBuilder();
                for (int i = 0; i < currentSb.length(); i++) {
                    if (currentSb.charAt(i) == 'L') {
                        newSb.append('L');
                        if (i == 1 && currentSb.charAt(i - 1) == '.') {
                            newSb.replace(i - 1, i, "L");
                        } else if (i > 1
                                && currentSb.charAt(i - 1) == '.'
                                && currentSb.charAt(i - 2) != 'R') {
                            newSb.replace(i - 1, i, "L");
                        }
                    } else if (currentSb.charAt(i) == 'R') {
                        newSb.append('R');
                        if (i == currentSb.length() - 2 && currentSb.charAt(i + 1) == '.') {
                            newSb.replace(i + 1, i + 2, "R");
                            i++;
                        } else if (i < currentSb.length() - 2
                                && currentSb.charAt(i + 1) == '.'
                                && currentSb.charAt(i + 2) != 'L') {
                            newSb.replace(i + 1, i + 2, "R");
                            i++;
                        }
                    } else {
                        newSb.append('.');
                    }
                }
                currentSb.setLength(0);
                currentSb = newSb;
            } while (visited.add(currentSb.toString()));
            return currentSb.toString();
        }
    }
}