Fibonacci Number

Author: anantkaushik

509-fibonacci-number.py

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+"""
+Problem Link: https://leetcode.com/problems/fibonacci-number/
+
+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:
+    def fib(self, N):
+        """
+        :type N: int
+        :rtype: int
+        """
+        if N == 0:
+            return 0
+        l = [0,1]
+        for i in range(2,N):
+            s = l[i-1] + l[i-2]
+            l.append(s)
+        return l[N-1] + l[N-2]