enhancement: check spelling and update topic (#1943)

Co-authored-by: Subhrodip Mohanta <hello@subho.xyz>
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Ilkka Seppälä 2022-01-08 14:33:19 +02:00 committed by GitHub
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3 changed files with 23 additions and 24 deletions

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@ -17,19 +17,19 @@ and to interleave the execution of functions without hard coding them together.
## Explanation ## Explanation
Recursion is a frequently adopted technique for solving algorithmic problems in a divide and conquer Recursion is a frequently adopted technique for solving algorithmic problems in a divide and conquer
style. For example calculating fibonacci accumulating sum and factorials. In these kinds of problems style. For example, calculating Fibonacci accumulating sum and factorials. In these kinds of
recursion is more straightforward than their loop counterpart. Furthermore recursion may need less problems, recursion is more straightforward than its loop counterpart. Furthermore, recursion may
code and looks more concise. There is a saying that every recursion problem can be solved using need less code and looks more concise. There is a saying that every recursion problem can be solved
a loop with the cost of writing code that is more difficult to understand. using a loop with the cost of writing code that is more difficult to understand.
However recursion type solutions have one big caveat. For each recursive call it typically needs However, recursion-type solutions have one big caveat. For each recursive call, it typically needs
an intermediate value stored and there is a limited amount of stack memory available. Running out of an intermediate value stored and there is a limited amount of stack memory available. Running out of
stack memory creates a stack overflow error and halts the program execution. stack memory creates a stack overflow error and halts the program execution.
Trampoline pattern is a trick that allows us define recursive algorithms in Java without blowing the Trampoline pattern is a trick that allows defining recursive algorithms in Java without blowing the
stack. stack.
Real world example Real-world example
> A recursive Fibonacci calculation without the stack overflow problem using the Trampoline pattern. > A recursive Fibonacci calculation without the stack overflow problem using the Trampoline pattern.
@ -105,6 +105,12 @@ public interface Trampoline<T> {
Using the `Trampoline` to get Fibonacci values. Using the `Trampoline` to get Fibonacci values.
```java ```java
public static void main(String[] args) {
LOGGER.info("Start calculating war casualties");
var result = loop(10, 1).result();
LOGGER.info("The number of orcs perished in the war: {}", result);
}
public static Trampoline<Integer> loop(int times, int prod) { public static Trampoline<Integer> loop(int times, int prod) {
if (times == 0) { if (times == 0) {
return Trampoline.done(prod); return Trampoline.done(prod);
@ -112,17 +118,13 @@ Using the `Trampoline` to get Fibonacci values.
return Trampoline.more(() -> loop(times - 1, prod * times)); return Trampoline.more(() -> loop(times - 1, prod * times));
} }
} }
log.info("start pattern");
var result = loop(10, 1).result();
log.info("result {}", result);
``` ```
Program output: Program output:
``` ```
start pattern 19:22:24.462 [main] INFO com.iluwatar.trampoline.TrampolineApp - Start calculating war casualties
result 3628800 19:22:24.472 [main] INFO com.iluwatar.trampoline.TrampolineApp - The number of orcs perished in the war: 3628800
``` ```
## Class diagram ## Class diagram
@ -133,8 +135,8 @@ result 3628800
Use the Trampoline pattern when Use the Trampoline pattern when
* For implementing tail recursive function. This pattern allows to switch on a stackless operation. * For implementing tail-recursive functions. This pattern allows to switch on a stackless operation.
* For interleaving the execution of two or more functions on the same thread. * For interleaving execution of two or more functions on the same thread.
## Known uses ## Known uses

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@ -107,6 +107,4 @@ public interface Trampoline<T> {
} }
}; };
} }
} }

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@ -39,9 +39,9 @@ public class TrampolineApp {
* Main program for showing pattern. It does loop with factorial function. * Main program for showing pattern. It does loop with factorial function.
*/ */
public static void main(String[] args) { public static void main(String[] args) {
LOGGER.info("start pattern"); LOGGER.info("Start calculating war casualties");
var result = loop(10, 1).result(); var result = loop(10, 1).result();
LOGGER.info("result {}", result); LOGGER.info("The number of orcs perished in the war: {}", result);
} }
@ -55,5 +55,4 @@ public class TrampolineApp {
return Trampoline.more(() -> loop(times - 1, prod * times)); return Trampoline.more(() -> loop(times - 1, prod * times));
} }
} }
} }