[CountingElements] Codility-PermCheck

Author: Seogeurim

README.md

@@ -51,6 +51,7 @@
 | 01  |     | [Codility-Lesson2 CyclicRotation](./src/Array/CyclicRotation)               |      |
 | 02  |     | [Codility-Lesson2 OddOccurrencesInArray](./src/Array/OddOccurrencesInArray) |      |
 | 03  |     | [Codility-Lesson4 FrogRiverOne](./src/Array/FrogRiverOne)                   |      |
+| 04  |     | [Codility-Lesson4 PermCheck](./src/Array/PermCheck)                         |      |
 
 ### Stack
 

src/Array/PermCheck/Main.java

@@ -0,0 +1,23 @@
+package Array.PermCheck;
+
+public class Main {
+    public static void main(String[] args) {
+        Solution sol = new Solution();
+        System.out.println(sol.solution(new int[]{4, 1, 3, 2}));
+        System.out.println(sol.solution(new int[]{4, 1, 3}));
+    }
+}
+
+class Solution {
+    public int solution(int[] A) {
+        boolean[] check = new boolean[A.length + 1];
+        for (int value : A) {
+            if (value > A.length) return 0;
+            check[value] = true;
+        }
+        for (int i = 1; i <= A.length; i++) {
+            if (!check[i]) return 0;
+        }
+        return 1;
+    }
+}

src/Array/PermCheck/README.md

@@ -0,0 +1,5 @@
+## [Codility - Lesson 4 Counting Elements] PermCheck
+
+> Detected time complexity : **O(N) or O(N * log(N))**
+
+![image](https://user-images.githubusercontent.com/22045163/104466321-6fbf7200-55f8-11eb-87f8-949a7dd4f0c1.png)