695. 岛屿的最大面积

问题695 岛屿的最大面积 ★★☆☆☆

https://leetcode-cn.com/problems/max-area-of-island/

BFS的解法并不难理解。从某个点开始，上下左右四个方向，联通的点入队列，同时，为了避免重复，借助一个visited的布尔数组。

	int[] dx = new int[] {0, -1, 0, 1};
	int[] dy = new int[] {1, 0, -1, 0};

	public int maxAreaOfIsland(int[][] grid) {
		int maxArea = 0;

		int m = grid.length;
		int n = grid[0].length;

		Queue<int[]> queue = new LinkedList<>();

		boolean[][] visited = new boolean[m][n];

		for (int i = 0; i < m; i++) {
			for (int j = 0; j < n; j++) {
				if (grid[i][j] == 1 && visited[i][j] == false) {
					queue.clear();

					queue.add(new int[] {i, j});
					visited[i][j] = true;
					int area = 1;
					while (!queue.isEmpty()) {
						int[] cur = queue.poll();
						for (int k = 0; k < 4; k++) {
							int nextRow = cur[0] + dx[k];
							int nextCol = cur[1] + dy[k];
							if (nextRow >= 0 && nextRow < m
								&& nextCol >= 0 && nextCol < n
								&& grid[nextRow][nextCol] == 1
								&& visited[nextRow][nextCol] == false) {
								queue.add(new int[] {nextRow, nextCol});
								visited[nextRow][nextCol] = true;
								area++;
							}
						}
					}

					if (area > maxArea) {
						maxArea = area;
					}
				}
			}
		}

		return maxArea;
	}

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