package LeetCode;

import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Deque;

public class LC_200 {
    static int[][] move = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
    static Deque<int[]> deque = new ArrayDeque<>();

    public static void main(String[] args) {
        char[][] grid = {
                {'1', '1', '0', '0', '0'},
                {'1', '1', '0', '0', '0'},
                {'0', '0', '1', '0', '0'},
                {'0', '0', '0', '1', '1'}};
        System.out.println(numIslands(grid));
    }

    public static int numIslands(char[][] grid) {

        boolean[][] visited = new boolean[grid.length][grid[0].length];
        //Arrays.fill(visited, false);
        int res = 0;
        for (int i = 0; i < grid.length; i++) {
            for (int j = 0; j < grid[0].length; j++) {
                if (!visited[i][j] && grid[i][j] == '1') {
                    deque.offer(new int[]{i, j});
                    bfs(grid, visited);
                    res++;
                }
            }
        }
        return res;
    }

    public static void bfs(char[][] grid, boolean[][] visited) {
        while (!deque.isEmpty()) {
            int x = deque.getFirst()[0];
            int y = deque.getFirst()[1];
            deque.removeFirst();
            for (int i = 0; i < move.length; i++) {
                int nestx = x + move[i][0];
                int nexty = y + move[i][1];
                if (nestx < 0 || nestx >= grid.length || nexty < 0 || nexty >= grid[0].length) continue;
                else {
                    if (!visited[nestx][nexty] && grid[nestx][nexty] == '1') {
                        deque.offer(new int[]{nestx, nexty});
                        visited[nestx][nexty] = true;
                    }
                }
            }
        }

    }

}