[TimeComplexity] Codility-PermMissingElem

Author: Seogeurim

README.md

@@ -67,6 +67,7 @@
 | 04  |     | [Baekjoon-2748 피보나치 수 2](./src/TimeComplexity/P2748) | DP                        |
 | 05  |     | [Baekjoon-1806 부분합](./src/TimeComplexity/P1806)        | 2-pointer                 |
 | 06  |     | [Codility-Lesson3 FrogJmp](./src/TimeComplexity/FrogJmp)    |      |
+| 06  |     | [Codility-Lesson3 PermMissingElem](./src/TimeComplexity/PermMissingElem)    |      |
 
 ## Data Structure
 

src/TimeComplexity/PermMissingElem/Main.java

@@ -0,0 +1,20 @@
+package TimeComplexity.PermMissingElem;
+
+public class Main {
+    public static void main(String[] args) {
+        Solution sol = new Solution();
+        System.out.println(sol.solution(new int[]{}));
+        System.out.println(sol.solution(new int[]{2, 3, 1, 5}));
+    }
+}
+
+class Solution {
+    public int solution(int[] A) {
+        boolean[] checked = new boolean[A.length + 2];
+        for (int a : A) checked[a] = true;
+        for (int i = 1; i < checked.length; i++) {
+            if (!checked[i]) return i;
+        }
+        return A.length + 1;
+    }
+}

src/TimeComplexity/PermMissingElem/README.md

@@ -0,0 +1,5 @@
+## [Codility - Lesson 3 Time Complexity] PermMissingElem
+
+> Detected time complexity : **O(N) or O(N * log(N))**
+
+![image](https://user-images.githubusercontent.com/22045163/101918025-361bd580-3c0c-11eb-96f3-7626764d8ece.png)