New Problem C++ Solution - "Fibonacci Number"

README.md

@@ -66,7 +66,7 @@ LeetCode
 |532|[K-diff Pairs in an Array](https://leetcode.com/problems/k-diff-pairs-in-an-array/) | [Python](./algorithms/python/K-diffPairsInAnArray/findPairs.py)|Easy|
 |520|[Detect Capital](https://leetcode.com/problems/detect-capital/) | [C++](./algorithms/cpp/detectCapital/DetectCapital.cpp)|Easy|
 |518|[Coin Change 2](https://leetcode.com/problems/coin-change-2/) | [C++](./algorithms/cpp/coinChange/CoinChange2.cpp)|Medium|
-|509|[Fibonacci Number](https://leetcode.com/problems/fibonacci-number/) | [Python](./algorithms/python/FibonacciNumber/fib.py)|Easy|
+|509|[Fibonacci Number](https://leetcode.com/problems/fibonacci-number/) | [C++](./algorithms/cpp/fibonacciNumber/FibonacciNumber.cpp), [Python](./algorithms/python/FibonacciNumber/fib.py)|Easy|
 |477|[Total Hamming Distance](https://leetcode.com/problems/total-hamming-distance/) | [C++](./algorithms/cpp/totalHammingDistance/totalHammingDistance.cpp)|Medium|
 |463|[Island Perimeter](https://leetcode.com/problems/island-perimeter/) | [C++](./algorithms/cpp/islandPerimeter/IslandPerimeter.cpp)|Easy|
 |450|[DeleteNodeInABST](https://leetcode.com/problems/delete-node-in-a-bst/) | [Python](./algorithms/python/DeleteNodeInABST/deleteNode.py)|Medium|

algorithms/cpp/fibonacciNumber/FibonacciNumber.cpp

@@ -0,0 +1,50 @@
+// Source : https://leetcode.com/problems/fibonacci-number/
+// Author : Hao Chen
+// Date   : 2019-03-26
+
+/***************************************************************************************************** 
+ *
+ * The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence, such 
+ * that each number is the sum of the two preceding ones, starting from 0 and 1. That is,
+ * 
+ * F(0) = 0,   F(1) = 1
+ * F(N) = F(N - 1) + F(N - 2), for N > 1.
+ * 
+ * Given N, calculate F(N).
+ * 
+ * Example 1:
+ * 
+ * Input: 2
+ * Output: 1
+ * Explanation: F(2) = F(1) + F(0) = 1 + 0 = 1.
+ * 
+ * Example 2:
+ * 
+ * Input: 3
+ * Output: 2
+ * Explanation: F(3) = F(2) + F(1) = 1 + 1 = 2.
+ * 
+ * Example 3:
+ * 
+ * Input: 4
+ * Output: 3
+ * Explanation: F(4) = F(3) + F(2) = 2 + 1 = 3.
+ * 
+ * Note:
+ * 
+ * 0 ≤ N ≤ 30.
+ ******************************************************************************************************/
+
+class Solution {
+public:
+    int fib(int N) {
+        if (N < 2 )  return N;
+        int first = 0, second = 1;
+
+        for ( N-=1; N > 0; N-- ) {
+            second += first;
+            first = second - first;
+        }
+        return second;
+    }
+};