Cpp solutions (#44)

* Added-required-code

* Added-solution

* Updated

* formated-readme

Author: trivediavinash

C++/Best-Time-to-Buy-and-Sell-Stock-II.cpp

@@ -0,0 +1,32 @@
+/*Runtime: 8 ms, faster than 96.30% of C++ online submissions for Best Time to Buy and Sell Stock II.
+Memory Usage: 13.4 MB, less than 5.04% of C++ online submissions for Best Time to Buy and Sell Stock II.
+*/
+
+class Solution
+{
+	public:
+		int maxProfit(vector<int> &prices)
+		{
+			int sum = 0;
+			//If the number of element in the array are zero or one just return zero.
+			if (prices.size() == 1 or prices.size() == 0)
+			{
+				return 0;
+			}
+
+			//Traverse the array and compare the consecutive two elements .
+			for (int i = 0; i < prices.size() - 1; i++)
+			{
+				// If first consecuitve element is less than second subtract both and add in the sum varibale. 
+				if (prices[i] < prices[i + 1])
+				{
+					sum += prices[i + 1] - prices[i];
+
+				}
+			}
+
+			//Finally return the sum.
+			return sum;
+
+		}
+};

C++/Linked-List-Cycle-II.cpp

@@ -0,0 +1,33 @@
+
+class Solution
+{
+	public:
+		ListNode* detectCycle(ListNode *head)
+		{
+			//If head is null or head->next is null dont do anything just return.
+			if (!head) return NULL;
+			if (head->next == NULL) return NULL;
+			//Take two pointers slow and fast both initially pointing to head .  
+			ListNode *fast = head;
+			ListNode *slow = head;
+			while (fast and fast->next)
+			{
+				// Move fast pointer two step and slow pointer one step forward.
+				fast = fast->next->next;
+				slow = slow->next;
+				//At some time if fast and slow are equal it means there is a cycle .
+				if (fast == slow) break;
+			}
+
+			if (fast == NULL or fast->next == NULL) return NULL;
+			//Now we point one pointer to head and increment both  the pointers one step untill slow and fast pointer do not become equal.
+			slow = head;
+			while (slow != fast)
+			{
+				slow = slow->next;
+				fast = fast->next;
+			}
+
+			return slow;
+		}
+};

C++/Single-Number.cpp

@@ -0,0 +1,27 @@
+/*This solition is the most optiized solution
+
+    Time Complexity: O(N)
+    Space Complexity: O(1)
+
+*/
+
+class Solution
+{
+	public:
+		int singleNumber(vector<int> &nums)
+		{
+			//initialised the xor of numbers in xorr variable
+			int xorr = 0;
+			//Linearly traversing the array
+			for (auto x = 0; x < nums.size(); x++)
+			{
+				//Calculating Xor of two numbers .
+				xorr = xorr ^ nums[x];
+
+			}
+
+			// Atlast return the final xor .
+
+			return xorr;
+		}
+};

README.md

@@ -70,7 +70,7 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
 
 | #    | Title                                                                 | Solution                                                                   | Time   | Space  | Difficulty | Tag | Note      |
 | ---- | --------------------------------------------------------------------- | -------------------------------------------------------------------------- | ------ | ------ | ---------- | --- | --------- |
-| 0136 | [Single Number](https://leetcode.com/problems/single-number/)         | [Java](./Java/single-number.java) <br> [Python](./Python/single-number.py) | _O(n)_ | _O(1)_ | Easy       |     | Using XOR |
+| 0136 | [Single Number](https://leetcode.com/problems/single-number/)         | [Java](./Java/single-number.java) <br> [Python](./Python/single-number.py) <br> [C++](./C++/Single-Number.cpp) | _O(n)_ | _O(1)_ | Easy       |     | Using XOR |
 | 0260 | [Single Number III](https://leetcode.com/problems/single-number-iii/) | [Python](./Python/single-number-iii.py)                                    | _O(n)_ | _O(1)_ | Medium     |     |           |
 | 0520 | [Detect Capital Use](https://leetcode.com/problems/detect-capital/)   | [Python](./Python/detect-capital.py)                                       | _O(n)_ | _O(1)_ | Easy       |     |           |
 
@@ -89,7 +89,7 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
 | 697 | [Degree of an Array](https://leetcode.com/problems/degree-of-an-array) | [Java](./Java/Degree-of-an-Array.java)              | _O(n)_     | _O(n)_ | Easy       | Array     |      |
 | 1089 | [Duplicate Zeroes](https://leetcode.com/problems/duplicate-zeros/)     | [JavaScript](./JavaScript/Duplicate-Zeroes.js) | _O(n)_     | _O(n)_ | Easy       | Array     |      |
 | 1502 | [Can Make Arithmetic Progression From Sequence](https://leetcode.com/problems/can-make-arithmetic-progression-from-sequence/)     | [Java](./Java/can-make-arithmetic-progression-from-sequence.java) | _O(n)_     | _O(1)_ | Easy       | Array     |      |
-| 122  | [Best Time to buy and sell Stock II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii)       | [Python](./Python/best-time-to-buy-and-sell-stock-ii.py)        | _O(N)_ | _O(1)_ | Medium     | Stocks |      |
+| 122  | [Best Time to buy and sell Stock II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii)       | [Python](./Python/best-time-to-buy-and-sell-stock-ii.py)   <br> [C++](./C++/Best-Time-to-Buy-and-Sell-Stock-II.cpp)     | _O(N)_ | _O(1)_ | Medium     | Stocks |      |
 | 119  | [Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii)       | [Python](./Python/pascals-triangle-ii.py)        | _O(N^2)_ | _O(K)_ | Easy     |  |      |
 | 1480  | [Running Sum of 1d Array](https://leetcode.com/problems/running-sum-of-1d-array/)       | [Java](./Java/running-sum-of-1d-array.java)        | _O(N)_ | _O(N)_ | Easy     | Simple sum |      |
 | 42  | [Trapping Rain Water](https://leetcode.com/problems/trapping-rain-water/)       | [Python](./Python/trapping_rain.py)        | _O(N^2)_ | _O(N)_ | Hard     | Array |      |
@@ -130,7 +130,7 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
 | 19  | [Remove Nth Node From End of List](https://leetcode.com/problems/remove-nth-node-from-end-of-list/)                   | [Java](./Java/remove-nth-node-from-end-of-list.java)          | _O(n)_ | _O(1)_ | Medium     | Two pointers       |      |
 | 109 | [Convert Sorted List to Binary Search Tree](https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree/) | [Java](./Java/convert-sorted-list-to-binary-search-tree.java) | _O(n)_ | _O(n)_ | Medium     | LinkedList         |      |
 | 141 | [Linked List Cycle](https://leetcode.com/problems/linked-list-cycle/)                                                 | [Java](./Java/linked-list-cycle.java)                         | _O(n)_ | _O(1)_ | Easy       | Slow-Fast Pointers |      |
-| 142 | [Linked List Cycle II](https://leetcode.com/problems/linked-list-cycle-ii/)                                                 | [Java](./Java/linked-list-cycle-ii.java)                         | _O(n)_ | _O(1)_ | Medium       | Slow-Fast Pointers |      |
+| 142 | [Linked List Cycle II](https://leetcode.com/problems/linked-list-cycle-ii/)                                           | [Java](./Java/linked-list-cycle-ii.java)  <br> [C++](./C++/Linked-List-Cycle-II.cpp)         | _O(n)_ | _O(1)_ | Medium  | Slow-Fast Pointers |      |
 | 146 | [LRU Cache](https://leetcode.com/problems/lru-cache/)                                                                 | [C++](./C++/LRU-Cache.cpp)                                    | _O(1)_ | _O(k)_ | Medium     | Hash Map           |      |
 | 186 | [Middle of the Linked List](https://leetcode.com/problems/middle-of-the-linked-list/)                                 | [Java](./Java/middle-of-the-linked-list.java)                 | _O(n)_ | _O(1)_ | Easy       | Two pointers       |      |