New Problem Solution "Island Perimeter"

Author: haoel

README.md

@@ -59,6 +59,7 @@ LeetCode
 |520|[Detect Capital](https://leetcode.com/problems/detect-capital/) | [C++](./algorithms/cpp/detectCapital/DetectCapital.cpp)|Easy|
 |509|[Fibonacci Number](https://leetcode.com/problems/fibonacci-number/) | [Python](./algorithms/python/FibonacciNumber/fib.py)|Easy|
 |477|[Total Hamming Distance](https://leetcode.com/problems/total-hamming-distance/) | [C++](./algorithms/cpp/totalHammingDistance/totalHammingDistance.cpp)|Medium|
+|463|[Island Perimeter](https://leetcode.com/problems/island-perimeter/) | [C++](./algorithms/cpp/islandPerimeter/IslandPerimeter.cpp)|Easy|
 |450|[DeleteNodeInABST](https://leetcode.com/problems/delete-node-in-a-bst/) | [Python](./algorithms/python/DeleteNodeInABST/deleteNode.py)|Medium|
 |449|[Serialize and Deserialize BST](https://leetcode.com/problems/serialize-and-deserialize-bst/) | [Python](./algorithms/python/SerializeAndDeserializeBST/serialize.py)|Medium|
 |437|[Path Sum III](https://leetcode.com/problems/path-sum-iii/) | [Python](./algorithms/python/PathSumIII/pathSum.py)|Medium|

algorithms/cpp/islandPerimeter/IslandPerimeter.cpp

@@ -0,0 +1,56 @@
+// Source : https://leetcode.com/problems/island-perimeter/
+// Author : Hao Chen
+// Date   : 2019-02-04
+
+/***************************************************************************************************** 
+ *
+ * You are given a map in form of a two-dimensional integer grid where 1 represents land and 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" (water inside that 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:
+ * 
+ * Input:
+ * [[0,1,0,0],
+ *  [1,1,1,0],
+ *  [0,1,0,0],
+ *  [1,1,0,0]]
+ * 
+ * Output: 16
+ * 
+ * Explanation: The perimeter is the 16 yellow stripes in the image below:
+ * 
+ ******************************************************************************************************/
+class Solution {
+public:
+    int edge(vector<vector<int>> &grid, int x, int y) {
+        int edge = 0;
+        
+        if (x==0 || (x>0 && grid[x-1][y] == 0 ) ) edge++; //up
+        if (y==0 || (y>0 && grid[x][y-1] == 0 ) ) edge++; //left
+        if (x == grid.size() - 1 || 
+            (x < grid.size() - 1 && grid[x+1][y] == 0)) edge++; //down
+        if (y == grid[0].size() - 1 || 
+            (y < grid[0].size() - 1 && grid[x][y+1] == 0)) edge++; //right
+        
+        return edge;
+    }
+            
+    int islandPerimeter(vector<vector<int>>& grid) {
+        int perimeter = 0;
+        for(int i=0; i<grid.size(); i++) {
+            for(int j=0; j<grid[0].size(); j++) {
+                if (grid[i][j] == 1) {
+                    perimeter += edge (grid, i, j);
+                }
+            }
+        }
+        return perimeter;
+    }
+};