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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; import java.util.Map;
/** /**
*
* @author Varun Upadhyay (https://github.com/varunu28) * @author Varun Upadhyay (https://github.com/varunu28)
* * @author yanglbme (https://github.com/yanglbme)
*/ */
public class Fibonacci { 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 { 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 * This method finds the nth fibonacci number using memoization technique
* *
* @param n The input n for which we have to determine the fibonacci number * @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) { private static int fibMemo(int n) {
if (map.containsKey(n)) { if (map.containsKey(n)) {
return map.get(n); return map.get(n);
@ -42,10 +36,9 @@ public class Fibonacci {
if (n <= 2) { if (n <= 2) {
f = 1; f = 1;
} } else {
else { f = fibMemo(n - 1) + fibMemo(n - 2);
f = fibMemo(n-1) + fibMemo(n-2); map.put(n, f);
map.put(n,f);
} }
return f; return f;
@ -55,55 +48,50 @@ public class Fibonacci {
* This method finds the nth fibonacci number using bottom up * This method finds the nth fibonacci number using bottom up
* *
* @param n The input n for which we have to determine the fibonacci number * @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) { 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++) { for (int i = 1; i < n + 1; i++) {
int f = 1; int f;
if (i<=2) { if (i <= 2) {
f = 1; f = 1;
} } else {
else { f = fib.get(i - 1) + fib.get(i - 2);
f = fib.get(i-1) + fib.get(i-2);
} }
fib.put(i, f); fib.put(i, f);
} }
return fib.get(n); return fib.get(n);
} }
/** /**
* This method finds the nth fibonacci number using bottom up * 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 * @param n The input n for which we have to determine the fibonacci number
* Outputs the nth fibonacci number * Outputs the nth fibonacci number
* * <p>
* This is optimized version of Fibonacci Program. Without using Hashmap and recursion. * This is optimized version of Fibonacci Program. Without using Hashmap and recursion.
* It saves both memory and time. * It saves both memory and time.
* Space Complexity will be O(1) * Space Complexity will be O(1)
* Time Complexity will be O(n) * Time Complexity will be O(n)
* * <p>
* Whereas , the above functions will take O(n) Space. * Whereas , the above functions will take O(n) Space.
* @author Shoaib Rayeen (https://github.com/shoaibrayeen)
**/ **/
private static int fibOptimized(int n) { private static int fibOptimized(int n) {
if (n == 0) { if (n == 0) {
return 0; return 0;
} }
int prev = 0 , res = 1 , next; int prev = 0, res = 1, next;
for ( int i = 2; i < n; i++) { for (int i = 2; i < n; i++) {
next = prev + res; next = prev + res;
prev = res; prev = res;
res = next; res = next;
} }
return res; return res;
} }
} }