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Merge pull request #649 from shoaibrayeen/patch-1
Optimized Version [Without Hashmap & recursion]
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@ -29,6 +29,10 @@ public class Fibonacci {
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* Outputs the nth fibonacci number
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* Outputs the nth fibonacci number
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**/
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**/
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private static int fibMemo(int n) {
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private static int fibMemo(int n) {
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if (map.containsKey(n)) {
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if (map.containsKey(n)) {
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return map.get(n);
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return map.get(n);
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@ -71,5 +75,35 @@ public class Fibonacci {
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return fib.get(n);
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return fib.get(n);
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}
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}
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/**
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* This method finds the nth fibonacci number using bottom up
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*
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* @author Shoaib Rayeen (https://github.com/shoaibrayeen)
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* @param n The input n for which we have to determine the fibonacci number
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* Outputs the nth fibonacci number
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*
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* This is optimized version of Fibonacci Program. Without using Hashmap and recursion.
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* It saves both memory and time.
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* Space Complexity will be O(1)
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* Time Complexity will be O(n)
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*
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* Whereas , the above functions will take O(n) Space.
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**/
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private static int fibOptimized(int n) {
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if (n == 0) {
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return 0;
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}
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int prev = 0 , res = 1 , next;
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for ( int i = 2; i < n; i++) {
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next = prev + res;
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prev = res;
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res = next;
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}
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return res;
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}
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}
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}
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