RemoveDuplicatesfromSortedArray

Author: jackzhenguo

Array/Array.Lib/RemoveDuplicatesfromSortedArray.cs

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+/* ==============================================================================
+ * 功能描述：ThirdMaximumNumber  
+ * 创 建 者：gz
+ * 创建日期：2017/4/21 8:25:57
+ * ==============================================================================*/
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+//Given a non-empty array of integers, return the third maximum number in this array. If it does not exist, return the maximum number. The time complexity must be in O(n).
+
+//Example 1: 
+//Input: [3, 2, 1]
+
+//Output: 1
+
+//Explanation: The third maximum is 1. 
+//Example 2: 
+//Input: [1, 2]
+
+//Output: 2
+
+//Explanation: The third maximum does not exist, so the maximum (2) is returned instead. 
+//Example 3: 
+//Input: [2, 2, 3, 1]
+
+//Output: 1
+
+//Explanation: Note that the third maximum here means the third maximum distinct number. 
+//Both numbers with value 2 are both considered as second maximum.
+namespace Array.Lib
+{
+    /// <summary>
+    /// #414 : Third Maximum Number
+    /// </summary>
+    public class ThirdMaximumNumber
+    {
+        public int GetThirdMax(int[] a)
+        {
+            int first = a.Max();
+            int[] a2 = a.Where(r => r != first).ToArray();
+            if (a2.Length == 0)
+                return first;
+            int second = a2.Max();
+            int[] a3 = a2.Where(r => r != second).ToArray();
+            if (a3.Length == 0)
+                return first;
+            return a3.Max();
+        }
+
+    }
+}