From f98914fb299e105c24ab3f6f5d9624c5aeb97cdb Mon Sep 17 00:00:00 2001
From: Vatsalya Gupta <64428075+vatsalya-gupta@users.noreply.github.com>
Date: Fri, 2 Oct 2020 15:35:26 +0530
Subject: [PATCH] Create fibonacciBottomUp.cpp

---
 fibonacciBottomUp.cpp | 55 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 fibonacciBottomUp.cpp

diff --git a/fibonacciBottomUp.cpp b/fibonacciBottomUp.cpp
new file mode 100644
index 0000000..fa7c728
--- /dev/null
+++ b/fibonacciBottomUp.cpp
@@ -0,0 +1,55 @@
+//In the bottom-up dynamic programming approach, we’ll reorganize the order in which we solve the subproblems
+//This will allow us to use less memory space in our code.
+#include <iostream>
+using namespace std;
+
+//space O(n)
+int fib(int n,int dp[]){
+	for(int i=2;i<=n;i++){
+		dp[i]=dp[i-1]+dp[i-2];
+	}
+	return dp[n];
+}
+
+//space O(1)
+int fib_Space_Opt(int n){
+	//base case
+	if(n == 0 || n == 1) return n;
+
+	int a = 0;
+	int b = 1;
+	int c;
+
+	for(int i=2;i<=n;i++){
+		c = a + b;
+		a = b;
+		b = c;
+	}
+	return c;
+}
+
+
+int main() {
+ int n;
+ cout<<"Enter number 'n' to find nth fibonacci number: ";
+ cin>>n;
+ int dp[n+1]={0};
+ dp[1] = 1;
+
+ cout<<"Output calculated with space complexity O(n): ";
+ cout<<fib(n,dp)<<endl;
+ cout<<"Output calculated with space complexity O(1): ";
+ cout<<fib_Space_Opt(n)<<endl;
+
+return 0;
+}
+
+/*
+sample input output
+input: 10
+output: 55
+*/
+
+/*
+Time O(n)
+*/