Leetcode 54 - Spiral matrix - Being an interviewer - February 1, 2018

Leetcode54_SpiralMatrix_BeingInterviewer_p2.java

import java.io.*;
import java.util.*;

/*
 * To execute Java, please define "static void main" on a class
 * named Solution.
 *
 * If you need more classes, simply define them inline.
 */

class Solution {
  public static void main(String[] args) {
    ArrayList<String> strings = new ArrayList<String>();
    strings.add("Hello, World!");
    strings.add("Welcome to CoderPad.");
    strings.add("This pad is running Java 8.");

    for (String string : strings) {
      System.out.println(string);
    }
  }
  
  
  public List<Integer> spiral(int[][] matrix) {
    
    List<Integer> results = new ArrayList<Integer>();
    
    if (matrix.length == 0)
      return results;
    
    int rows = matrix.length;
    int cols = matrix[0].length;
    
    boolean[][] visited = new boolean[rows][cols];
    
    int[] dr = {0, 1, 0, -1};
    int[] dc = {1, 0, -1, 0};
    
    int i = 0, j = 0;
    int count = 0;
    int dir = 0;
    while (count < m * n) {
      
      if (!visited[i][j]) {
        results.add(matrix[i][j]);
        visited[i][j] = true;
        count++;
        i += dr[dir];
        j += dc[dir];
         if (i == 0 || j == 0 || i == rows || j == cols) {
           if (++dir == 3)
            dir = 0;
         }
      } else {
        if (++dir == 3)
            dir = 0;
      }
    }
    
    return results;
  }
}