主題
題目連結：
題目意譯：
給定一個大小 m × n 的二維二元網格 grid，其代表著 '1'（陸地）和 '0'（水域）的地圖，回傳島嶼的個數。
一座島嶼為連接水平或鉛直方向相鄰的陸地並被水域包圍的陸塊。你可以假設 grid 的四個邊被水包圍。
限制：
m == grid.length
n == grid[i].length
1 ≦ m, n ≦ 300
grid[i][j] 只會是 '0' 或是 '1'。
範例測資：
範例 1：
輸入： grid = [
["1","1","1","1","0"],
["1","1","0","1","0"],
["1","1","0","0","0"],
["0","0","0","0","0"]
]
輸出： 1
範例 2：
輸入： grid = [
["1","1","0","0","0"],
["1","1","0","0","0"],
["0","0","1","0","0"],
["0","0","0","1","1"]
]
輸出： 3
解題思維：
經典的廣度優先搜尋（Breadth First Search，BFS）題型，基本上與這題雷同。只是現在不需要求島嶼的最大面積，只需要求島嶼個數即可。
此次分享到此為止，如有任何更加簡潔的想法或是有說明不清楚之地方，也煩請各位大大撥冗討論。
