프로그래머스: 단체사진 찍기

private static final int PEOPLE_COUNT = 8;
private static final String[] PEOPLE_NAMES = {"A", "C", "F", "J", "M", "N", "R", "T"};

private static int answer;
public int solution(int n, String[] data) {
    answer = 0;
    perm("", 0, new boolean[8], data);

    return this.answer;
}

private void perm(String perm, int depth, boolean[] isVisit, String[] data) {
    if (depth == PEOPLE_COUNT) {

        if (isCondition(perm, data)) {
            answer++;
        }
    }

    for (int i = 0; i < PEOPLE_COUNT; i++) {
        if (!isVisit[i]) {
            isVisit[i] = true;
            perm(perm + PEOPLE_NAMES[i], depth + 1, isVisit, data);
            isVisit[i] = false;
        }
    }
}

private boolean isCondition(String perm, String[] data) {
    boolean isCondition = true;

    for (int i = 0; i < data.length; i++) {
        char[] tochar = data[i].toCharArray();
        int people1 = perm.indexOf(tochar[0]);
        int people2 = perm.indexOf(tochar[2]);

        int interval = people1 > people2 ? people1 - people2 - 1 : people2 - people1 - 1;

        int requestInterval = tochar[4] - '0';
        if (tochar[3] == '=' && interval != requestInterval) {
            isCondition = false;
            break;
        }

        if (tochar[3] == '<' && interval >= requestInterval) {
            isCondition = false;
            break;
        }

        if (tochar[3] == '>' && interval <= requestInterval) {
            isCondition = false;
            break;
        }
    }

    return isCondition;
}

for (int i = 0; i < PEOPLE_COUNT; i++) {
    if (!isVisit[i]) {
        isVisit[i] = true;
        perm(perm + PEOPLE_NAMES[i], depth + 1, isVisit, data);
        isVisit[i] = false;
    }
}

assertEquals(3648, test.solution(2, new String[] {"N~F=0", "R~T>2"}));
assertEquals(0, test.solution(2, new String[] {"M~C<2", "C~M>1"}));