solve problem Third Maximum Number

Author: P-ppc

README.md

@@ -151,6 +151,7 @@ All solutions will be accepted!
 |849|[Maximize Distance To Closest Person](https://leetcode-cn.com/problems/maximize-distance-to-closest-person/description/)|[java/py/js](./algorithms/MaximizeDistanceToClosestPerson)|Easy|
 |674|[Longest Continuous Increasing Subsequence](https://leetcode-cn.com/problems/longest-continuous-increasing-subsequence/description/)|[java/py/js](./algorithms/LongestContinuousIncreasingSubsequence)|Easy|
 |234|[Palindrome Linked List](https://leetcode-cn.com/problems/palindrome-linked-list/description/)|[java/py/js](./algorithms/PalindromeLinkedList)|Easy|
+|414|[Third Maximum Number](https://leetcode-cn.com/problems/third-maximum-number/description/)|[java/py/js](./algorithms/ThirdMaximumNumber)|Easy|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/ThirdMaximumNumber/README.md

@@ -0,0 +1,2 @@
+# Third Maximum Number
+This problem is easy to solve by three times repeat

algorithms/ThirdMaximumNumber/Solution.java

@@ -0,0 +1,37 @@
+class Solution {
+    public int thirdMax(int[] nums) {
+        Integer maxNum = null,
+                secondNum = null,
+                thirdNum = null;
+        
+        for (int num : nums) {
+            if (maxNum == null) {
+                maxNum = num;
+            } else {
+                maxNum = Math.max(maxNum, num);
+            }
+        }
+        
+        for (int num : nums) {
+            if (num == maxNum) {
+                continue;
+            } else if (secondNum == null) {
+                secondNum = num;
+            } else {
+                secondNum = Math.max(secondNum, num);
+            }
+        }
+        
+        for (int num : nums) {
+            if (num == maxNum || num == secondNum) {
+                continue;
+            } else if (thirdNum == null) {
+                thirdNum = num;
+            } else {
+                thirdNum = Math.max(thirdNum, num);
+            }
+        }
+        
+        return thirdNum != null ? thirdNum : maxNum;
+    }
+}

algorithms/ThirdMaximumNumber/solution.js

@@ -0,0 +1,38 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var thirdMax = function(nums) {
+    let maxNum = null,
+        secondNum = null,
+        thirdNum = null
+    
+    nums.forEach(num => {
+        if (maxNum === null) {
+            maxNum = num
+        } else {
+            maxNum = Math.max(maxNum, num)
+        }
+    })
+    
+    nums.forEach(num => {
+        if (num === maxNum) {
+        } else if (secondNum === null) {
+            secondNum = num
+        } else {
+            secondNum = Math.max(secondNum, num)
+        }
+    })
+    
+    nums.forEach(num => {
+        if (num === maxNum || num === secondNum) {
+        } else if (thirdNum === null) {
+            thirdNum = num
+        } else {
+            thirdNum = Math.max(thirdNum, num)
+        }
+    })
+    
+    
+    return thirdNum !== null ? thirdNum : maxNum
+};

algorithms/ThirdMaximumNumber/solution.py

@@ -0,0 +1,33 @@
+class Solution(object):
+    def thirdMax(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        max_num = None
+        second_num = None
+        third_num = None
+        
+        for num in nums:
+            if max_num == None:
+                max_num = num
+            else:
+                max_num = max(max_num, num)
+        
+        for num in nums:
+            if num == max_num:
+                continue
+            elif second_num == None:
+                second_num = num
+            else:
+                second_num = max(second_num, num)
+        
+        for num in nums:
+            if num == max_num or num == second_num:
+                continue
+            elif third_num == None:
+                third_num = num
+            else:
+                third_num = max(third_num, num)
+                
+        return third_num if third_num != None else max_num