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fix: remove unnecesary assignation to fix #698

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- Fix #698
- Thanks @lprone
This commit is contained in:
yanglbme
2019-02-05 13:10:40 +08:00
parent f2f79821ac
commit bb670a2ceb
1 changed files with 30 additions and 42 deletions
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72
Dynamic Programming/Fibonacci.java
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@ -4,14 +4,13 @@ import java.util.HashMap;
import java.util.Map;
/**
*
* @author Varun Upadhyay (https://github.com/varunu28)
*
* @author yanglbme (https://github.com/yanglbme)
*/
public class Fibonacci {
private static Map<Integer,Integer> map = new HashMap<Integer,Integer>();
private static Map<Integer, Integer> map = new HashMap<>();
public static void main(String[] args) throws Exception {
@ -26,13 +25,8 @@ public class Fibonacci {
* This method finds the nth fibonacci number using memoization technique
*
* @param n The input n for which we have to determine the fibonacci number
* Outputs the nth fibonacci number
* Outputs the nth fibonacci number
**/
private static int fibMemo(int n) {
if (map.containsKey(n)) {
return map.get(n);
@ -42,10 +36,9 @@ public class Fibonacci {
if (n <= 2) {
f = 1;
}
else {
f = fibMemo(n-1) + fibMemo(n-2);
map.put(n,f);
} else {
f = fibMemo(n - 1) + fibMemo(n - 2);
map.put(n, f);
}
return f;
@ -55,55 +48,50 @@ public class Fibonacci {
* 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
* Outputs the nth fibonacci number
**/
private static int fibBotUp(int n) {
Map<Integer,Integer> fib = new HashMap<Integer,Integer>();
Map<Integer, Integer> fib = new HashMap<>();
for (int i=1;i<n+1;i++) {
int f = 1;
if (i<=2) {
for (int i = 1; i < n + 1; i++) {
int f;
if (i <= 2) {
f = 1;
}
else {
f = fib.get(i-1) + fib.get(i-2);
} else {
f = fib.get(i - 1) + fib.get(i - 2);
}
fib.put(i, f);
}
return fib.get(n);
}
/**
* This method finds the nth fibonacci number using bottom up
*
* @author Shoaib Rayeen (https://github.com/shoaibrayeen)
* @param n The input n for which we have to determine the fibonacci number
* Outputs the nth fibonacci number
*
* This is optimized version of Fibonacci Program. Without using Hashmap and recursion.
* It saves both memory and time.
* Space Complexity will be O(1)
* Time Complexity will be O(n)
*
* Whereas , the above functions will take O(n) Space.
* Outputs the nth fibonacci number
* <p>
* This is optimized version of Fibonacci Program. Without using Hashmap and recursion.
* It saves both memory and time.
* Space Complexity will be O(1)
* Time Complexity will be O(n)
* <p>
* Whereas , the above functions will take O(n) Space.
* @author Shoaib Rayeen (https://github.com/shoaibrayeen)
**/
private static int fibOptimized(int n) {
if (n == 0) {
return 0;
}
int prev = 0 , res = 1 , next;
for ( int i = 2; i < n; i++) {
next = prev + res;
prev = res;
res = next;
int prev = 0, res = 1, next;
for (int i = 2; i < n; i++) {
next = prev + res;
prev = res;
res = next;
}
return res;
}
}
}