You are given?row x col?grid?representing a map where?grid[i][j] = 1?represents?land and?grid[i][j] = 0?represents water.

Grid cells are connected?horizontally/vertically?(not diagonally). The?grid?is completely surrounded by water, and there is exactly one island (i.e., one or more connected land cells).

The island doesn't have "lakes", meaning the water inside isn't connected to the water around the island. One cell is a square with side length 1. The grid is rectangular, width and height don't exceed 100. Determine the perimeter of the island.

?

Example 1:

Input: grid = [[0,1,0,0],[1,1,1,0],[0,1,0,0],[1,1,0,0]]Output: 16Explanation: The perimeter is the 16 yellow stripes in the image above.

Example 2:

Input: grid = [[1]]Output: 4

Example 3:

Input: grid = [[1,0]]Output: 4

如果這個位置上是1，那么加4，當出現(xiàn)相鄰的時候，則需要減去2，所以遍歷左邊跟上邊的所有情況，因為右邊跟下邊會在后面i++，j++的時候遍歷到；

Runtime:?4 ms, faster than?100.00%?of?Java?online submissions for?Island Perimeter.

Memory Usage:?42.9 MB, less than?80.05%?of?Java?online submissions for?Island Perimeter.