Add solution #463

Author: JoshCrozier

README.md

@@ -113,6 +113,7 @@
 448|[Find All Numbers Disappeared in an Array](./0448-find-all-numbers-disappeared-in-an-array.js)|Easy|
 451|[Sort Characters By Frequency](./0451-sort-characters-by-frequency.js)|Medium|
 459|[Repeated Substring Pattern](./0459-repeated-substring-pattern.js)|Easy|
+463|[Island Perimeter](./0463-island-perimeter.js)|Medium|
 476|[Number Complement](./0476-number-complement.js)|Easy|
 500|[Keyboard Row](./0500-keyboard-row.js)|Easy|
 506|[Relative Ranks](./0506-relative-ranks.js)|Easy|

solutions/0463-island-perimeter.js

@@ -0,0 +1,36 @@
+/**
+ * 463. Island Perimeter
+ * https://leetcode.com/problems/island-perimeter/
+ * Difficulty: Medium
+ *
+ * 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.
+ */
+
+/**
+ * @param {number[][]} grid
+ * @return {number}
+ */
+var islandPerimeter = function(grid) {
+  let island = 0;
+  let adjacent = 0;
+
+  for (let i = 0; i < grid.length; i++) {
+    for (let j = 0; j < grid[0].length; j++) {
+      if (grid[i][j] === 1) {
+        island++;
+        if (i + 1 < grid.length && grid[i + 1][j] === 1) adjacent++;
+        if (j + 1 < grid[0].length && grid[i][j + 1] === 1) adjacent++;
+      }
+    }
+  }
+
+  return island * 4 - adjacent * 2;
+};