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Added Fibanacci using memoization #90

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Merged
merged 2 commits into from
Sep 10, 2017
Merged

Added Fibanacci using memoization #90

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0d4cfba
Added Fibanacci using memoization
varunu28 Sep 4, 2017
73e0594
Added bottom up approach
varunu28 Sep 4, 2017
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Added bottom up approach
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@varunu28
varunu28 committed Sep 4, 2017
commit 73e05940eae0a46fa4921ef1ecfb81fab4f91a76
30 changes: 28 additions & 2 deletions Dynamic Programming/Fibonacci.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,8 @@ public static void main(String[] args) throws Exception {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int n = Integer.parseInt(br.readLine());

System.out.println(fib(n)); // Returns 8 for n = 6
System.out.println(fibMemo(n)); // Returns 8 for n = 6
System.out.println(fibBotUp(n)); // Returns 8 for n = 6
}

/**
Expand All @@ -28,7 +29,7 @@ public static void main(String[] args) throws Exception {
* Outputs the nth fibonacci number
**/

public static int fib(int n) {
public static int fibMemo(int n) {
if (map.containsKey(n)) {
return map.get(n);
}
Expand All @@ -45,5 +46,30 @@ public static int fib(int n) {

return f;
}

/**
* This method finds the nth fibonacci number using bottom up
*
* @param n The input n for which we have to determine the fibonacci number
* Outputs the nth fibonacci number
**/

public static int fibBotUp(int n) {

Map<Integer,Integer> fib = new HashMap<Integer,Integer>();

for (int i=1;i<n+1;i++) {
int f = 1;
if (i<=2) {
f = 1;
}
else {
f = fib.get(i-1) + fib.get(i-2);
}
fib.put(i, f);
}

return fib.get(n);
}
}