DVR

Given an input string, return the commands need to input the string in a dvr. Commands are “l”, “r”, “u”, “d”, and “*”.

input was "bad" -> "r*l*rrr*"

[a] b  c  d  e
 f  g  h  i  j
 k  l  m  n  o
 p  q  r  s  t
 u  v  w  x  y
 z

// 

public String move(String word) {
    int[] prev = new int[2];  // init as (0, 0) = a

    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < word.length(); ++i) {
        int[] cur = charToCoord(word.charAt(i));
        sb.append(charMove(prev, cur));
        sb.append('*');
        prev = cur;
    }
    return sb.toString();
}

public int[] charToCoord(char c) {
    int[] coord = new int[2];  // (y, x)

    int idx = c - 'a';
    coord[0] = idx / 5;
    coord[0] = idx % 5;
    
    return coord;
}

public String charMove(int[] start, int[] end) {
    String result = "";
    final int dy = end[0] - start[0];
    final int dx = end[1] - start[1];
    if (dy == 0) {
        // start.y == end.y
        result = dxMove(dx);
    } else if (dy < 0) {
        // start.y > end.y, first go up, then go left/right
        result = dyMove(dy) + dxMove(dx);
    } else /* dy > 0 */ {
        // start.y < end.y, first go left/right, then go down
        result = dxMove(dx) + dyMove(dy);
    }
    return result;
}

public String dyMove(int dy) {
    if (dy > 0) {
        return repeat('d', dy);
    } else if (dy < 0) {
        return repeat('u', -dy);
    } else {
        return "";
    }
}

public String dxMove(int dx) {
    if (dx > 0) {
        return repeat('r', dx);
    } else if (dx < 0) {
        return repeat('l', -dx);
    } else {
        return "";
    }
}

public String repeat(char c, int times) {
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < times; ++i) {
        sb.append(c);
    }
    return sb.toString();
}