[LintCode] Number of Islands（岛屿个数）

[
  [1, 1, 0, 0, 0],
  [0, 1, 0, 0, 1],
  [0, 0, 0, 1, 1],
  [0, 0, 0, 0, 0],
  [0, 0, 0, 0, 1]
]

package com.ossez.lang.tutorial.tests.lintcode;

import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * <p>
 * 433
 * <ul>
 * <li>@see <a href=
 * "https://www.cwiki.us/display/ITCLASSIFICATION/Number+of+Islands">https://www.cwiki.us/display/ITCLASSIFICATION/Number+of+Islands</a>
 * <li>@see<a href="https://www.lintcode.com/problem/number-of-islands/">https://www.lintcode.com/problem/number-of-islands/</a>
 * </ul>
 * </p>
 * 
 * @author YuCheng
 *
 */
public class LintCode0433NumIslandsTest {

  private final static Logger logger = LoggerFactory.getLogger(LintCode0433NumIslandsTest.class);

  /**
   * 
   */
  @Test
  public void testMain() {
    logger.debug("BEGIN");
    // INIT GRID
    boolean[][] grid = { { true, true, false, false, false }, { false, true, false, false, true }, { false, false, false, true, true },
        { false, false, false, false, false }, { false, false, false, false, true }

    };

    // NULL CHECK
    if (grid.length == 0 || grid[0].length == 0) {
      System.out.println("NULL");
      // return 0;
    }

    // GET SIZE
    int n = grid.length;
    int m = grid[0].length;

    // ARRAY FOR VISITED LOG
    boolean[][] visited = new boolean[n][m];

    int count = 0;

    // LOOP FOR GRID
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        if (grid[i][j] && !visited[i][j]) {
          numIslandsDFS(grid, visited, i, j);
          count++;
        }
      }
    }

    System.out.println(count);

  }

  /**
   * 
   * @param grid
   * @param visited
   * @param x
   * @param y
   */
  public void numIslandsDFS(boolean[][] grid, boolean[][] visited, int x, int y) {
    if (x < 0 || x >= grid.length) {
      return;
    }

    if (y < 0 || y >= grid[0].length) {
      return;
    }

    if (grid[x][y] != true || visited[x][y]) {
      return;
    }

    visited[x][y] = true;

    // Recursive call
    numIslandsDFS(grid, visited, x - 1, y);
    numIslandsDFS(grid, visited, x + 1, y);
    numIslandsDFS(grid, visited, x, y - 1);
    numIslandsDFS(grid, visited, x, y + 1);

  }
}