Create 463-island-perimeter.js

aadil42 · web-flow · commit 72747d548b5b · 2022-11-08T17:13:39.000+05:30
solved island-perimeter in JS.
diff --git a/javascript/463-island-perimeter.js b/javascript/463-island-perimeter.js
@@ -0,0 +1,24 @@
+// problem link https://leetcode.com/problems/island-perimeter
+// time complexity. it looks O(n^2) but it's actually constant time O(1). Because the input widht  and height won't exeed 100 as stated in the problem.
+
+var islandPerimeter = function(grid) {
+        const row = grid.length;
+    const column = grid[0].length;
+    let perimeter = 0;
+    for(let i = 0; i < row; i++) {
+        for(let j = 0; j< column; j++) {
+            if(grid[i][j] == 1) {
+                perimeter += 4;
+
+                if(i > 0 && grid[i - 1][j] == 1) {
+                    perimeter -= 2;
+                }
+                if(j > 0 && grid[i][j - 1] == 1) {
+                    perimeter -= 2;
+                }
+            }
+        }
+    }
+
+    return perimeter
+};
