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Queues - Elizabeth Deutsch - Recursion-tracing #22

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Queues - Elizabeth Deutsch - Recursion-tracing #22

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50 changes: 25 additions & 25 deletions README.md
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Original file line number Diff line number Diff line change
@@ -1,14 +1,14 @@
# Recursion Problems

## Definitions
Define the following:
Define the following:

- Recursion
- Recursive Case
- Base Case
- Activation Chain/Stack
- Activation Record/Call
- Infinite Recursion/Stack Overflow/Stack too deep
- Recursion - Recursion is when a method calls itself (opposite of iterative).
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I wouldn't say "opposite" of iterative. Maybe "opposed" to iterative. But opposite seems weird to me.

- Recursive Case - The recursive case is what keeps the method going.
- Base Case - The base case of a recursive method is the stopping case - if it were not reached, the recursion would go on forever. There can be more than one base case.
- Activation Chain/Stack - the process of a recursive method as it is executed. Can be diagrammed with Crystal's bubble notation.
- Activation Record/Call - keeps track of values as the recursive method executes.
- Infinite Recursion/Stack Overflow/Stack too deep - Infinite recursion happens when a method never reaches a base case. The recrusion keeps going forever and results in error messages like "Stack Overflow" or "Stack too deep".
- Tail Recursion

## Tracing through a recursive method
Expand All @@ -24,9 +24,9 @@ def mystery1(n)
end
```

- What is mystery1(5)?
- What is mystery1(10)?
- What is mystery1(0)?
- What is mystery1(5)? 15
- What is mystery1(10)? 55
- What is mystery1(0)? Infinite recursion/Stack level too deep

### Trace #2
```
Expand All @@ -39,9 +39,9 @@ def mystery2(n)
end
```

- What is mystery2(123)?
- What is mystery2(9005)?
- What is mystery2(-123)?
- What is mystery2(123)? 6
- What is mystery2(9005)? 14
- What is mystery2(-123)? -123
- _Added Fun: How could we make `mystery2(-123)` work the way we might expect it to work instead of the way it does?_

### Trace #3
Expand All @@ -60,9 +60,9 @@ def mystery3(n)
end
```

- What is mystery3(1)?
- What is mystery3(13)?
- What is mystery3(-6)?
- What is mystery3(1)? 100
- What is mystery3(13)? 100
- What is mystery3(-6)? 200

### Trace #4
```
Expand All @@ -75,9 +75,9 @@ def mystery4(b,e)
end
```

- What is mystery4(10,2)?
- What is mystery4(4,3)?
- What is mystery4(5,0)?
- What is mystery4(10,2)? 100
- What is mystery4(4,3)? 64
- What is mystery4(5,0)? 1

### Trace #5
```
Expand All @@ -90,9 +90,9 @@ def mystery5(s)
end
```

- What is mystery5("hi")?
- What is mystery5("")?
- What is mystery5("Hi, there!")?
- What is mystery5("hi")? "**"
- What is mystery5("")? ""
- What is mystery5("Hi, there!")? "**********"
- _Added Fun: How could we make only alphabetic characters to be changed to stars?_

### Trace #6
Expand All @@ -110,7 +110,7 @@ def mystery6(s)
end
```

- What is mystery6("goodnight moon")?
- What is mystery6("Ada Developers Academy")?
- What is mystery6("Hi, there!")?
- What is mystery6("goodnight moon")? " moon goodnight"
- What is mystery6("Ada Developers Academy")? " Academy Developers Ada"
- What is mystery6("Hi, there!")? " there! Hi,"
- _Added Fun: How could we make the reversal happen by letter, instead of by word (i.e. Make it so that mystery6("goodnight moon") returned "noom thgindoog")?_