LightSwitchingPuzzle

package com.github.tauty.study.quiz;

import java.util.Arrays;

/**
 * Created by tetsuo.uchiumi on 12/17/14.
 */
public class LightSwitchingPuzzle {

    public static void main(String[] args) {
        new LightSwitchingPuzzle().execute();
    }

    private void execute() {
        System.out.println(minFlips("YYYYYY"));
        System.out.println(minFlips("YNYNYNYNY"));
        System.out.println(minFlips("NNNNNNNNNN"));
        System.out.println(minFlips("YYYNYYYNYYYNYYNYYYYN"));
        System.out.println(minFlips("NYNNYNNNYNNNNYNNNNNYNNNNNNYNNNNNNNY"));
    }

    public int minFlips(String state) {
        char[] chars = new char[state.length()];
        state.getChars(0, state.length(), chars, 0);
        return turn(chars, 0, 0);
    }

    private int turn(char[] chars, int index, int times) {
        System.out.println(Arrays.toString(chars));
        for (int i = index; i < chars.length; i++) {
            char c = chars[i];
            if(c == 'Y') {
                toggle(chars, i + 1);
                return turn(chars, i + 1, times + 1);
            }
        }
        return times;
    }

    private void toggle(char[] chars, final int DELTA) {
        for (int i = DELTA - 1; i < chars.length; i += DELTA) {
            chars[i] = chars[i] == 'Y' ? 'N' : 'Y';
        }
    }
}