231206 단어 변환

private boolean[] visit;
private int answer;

public int solution(String begin, String target, String[] words) {
	visit = new boolean[words.length];
	answer = 0;

	if (!containsTarget(target, words)) {
		return 0;
	}

	dfs(begin, target, words, 0);
	return answer;
}

private boolean containsTarget(String target, String[] words) {
	for (String word : words) {
		if (word.equals(target)) {
			return true;
		}
	}
	return false;
}

private void dfs(String begin, String target, String[] words, int depth) {
	if (begin.equals(target)) {
		answer = depth;
		return;
	}

	for (int i = 0; i < words.length; i++) {
		if (visit[i]) {
			continue;
		}

		int matchingChars = countMatchingChars(begin, words[i]);
		if (matchingChars == begin.length() - 1) {
			visit[i] = true;
			dfs(words[i], target, words, depth + 1);
			visit[i] = false;
		}
	}
}

private int countMatchingChars(String str1, String str2) {
	int count = 0;
	for (int j = 0; j < str1.length(); j++) {
		if (str1.charAt(j) == str2.charAt(j)) {
			count++;
		}
	}
	return count;
}

출처:https://school.programmers.co.kr/learn/courses/30/lessons/43163