add IslandPerimeter

Author: fishercoder1534

EASY/src/easy/IslandPerimeter.java

@@ -0,0 +1,21 @@
+package easy;
+
+public class IslandPerimeter {
+    /**Inspired by this post: https://discuss.leetcode.com/topic/68983/java-9-line-solution-add-4-for-each-land-and-remove-2-for-each-internal-edge
+     * 1. we increment the count by 4 whenever we encounter an island
+     * 2. also, we check in two directions: island's left and island's top, we only check these two directions,
+     * see if this island has any island neighbors, if so, we'll deduct two from it.*/
+    public int islandPerimeter(int[][] grid) {
+        int count = 0;
+        for (int i = 0; i < grid.length; i++) {
+            for (int j = 0; j < grid[0].length; j++) {
+                if(grid[i][j] == 1) {
+                    count += 4;
+                    if(i > 0 && grid[i-1][j] == 1) count -= 2;
+                    if(j > 0 && grid[i][j-1] == 1) count -= 2;
+                }
+            }
+        }
+        return count;
+    }
+}

InterviewQuestions/src/package1/LFUCache.java renamed to HARD/src/hard/LFUCache.java

@@ -1,6 +1,7 @@
 # fishercoderLeetcode
 |  #  |      Title     |   Solutions   | Time          | Space         | Difficulty  | Tag          | Notes
 |-----|----------------|---------------|---------------|---------------|-------------|--------------|-----
+|463|[Island Perimeter](https://leetcode.com/problems/island-perimeter/)|[Solution](../../blob/master/EASY/src/easy/IslandPerimeter.java)| O(m*n)|O(1) | Easy| 
 |459|[Repeated Substring Pattern](https://leetcode.com/problems/repeated-substring-pattern/)|[Solution](../../blob/master/EASY/src/easy/RepeatedSubstringPattern.java)| O(n)|O(n) | Easy| KMP
 |456|[132 Pattern](https://leetcode.com/problems/132-pattern/)|[Solution](../../blob/master/MEDIUM/src/medium/_132Pattern.java) | O(n) |O(n) | Medium| Stack
 |455|[Assign Cookies](https://leetcode.com/problems/assign-cookies/)|[Solution](../../blob/master/EASY/src/easy/AssignCookies.java)| O(n)|O(1) | Easy|