题解 | #岛屿数量#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 判断岛屿数量
     * @param grid char字符型二维数组
     * @return int整型
     */
    public int solve (char[][] grid) {
        int nr = grid.length;
        int nc = grid[0].length;
        int count = 0;
        for (int r = 0; r < nr; r++) {
            for (int c = 0; c < nc; c++) {
                if (grid[r][c] == '1') {
                    count++;
                    grid[r][c] = '0';
                    Queue<Integer> bfs = new LinkedList<>();
                    bfs.offer(r * nc + c);
                    while (!bfs.isEmpty()) {
                        int temp = bfs.poll();
                        int row = temp / nc;
                        int col = temp % nc;
                        if (row - 1 >= 0 && grid[row - 1][col] == '1') {
                            bfs.offer((row - 1) * nc + col);
                            grid[row - 1][col] = '0';
                        }
                        if (row + 1 < nr && grid[row + 1][col] == '1') {
                            bfs.offer((row + 1) * nc + col);
                            grid[row + 1][col] = '0';
                        }
                        if (col - 1 >= 0 && grid[row][col - 1] == '1') {
                            bfs.offer(row * nc + col - 1);
                            grid[row][col - 1] = '0';
                        }
                        if (col + 1 < nc && grid[row][col + 1] == '1') {
                            bfs.offer(row * nc + col + 1);
                            grid[row][col + 1] = '0';
                        }
                    }
                }
            }
        }
        return count;
    }
}