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refactor: slices 25th exercise

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Inanc Gumus
2019-08-18 14:03:08 +03:00
parent df18e1a4bd
commit 552a6a6cf7
3 changed files with 119 additions and 140 deletions
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164
16-slices/exercises/25-add-lines/main.go
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@ -1,47 +1,31 @@
package main
import (
"fmt"
"strings"
s "github.com/inancgumus/prettyslice"
)
//
// ! NOTE If the program does not work, please update your
// local copy of the prettyslice package:
//
// go get -u github.com/inancgumus/prettyslice
//
// ---------------------------------------------------------
// EXERCISE: Add newlines to the lyric sentences
// EXERCISE: Add a newline after each sentence
//
// You have a slice of lyrics data of Beatles' awesome
// song: Yesterday. Your goal is adding newlines after
// each sentence of the lyric.
// You have a slice that contains Beatles' awesome song:
// Yesterday. You want to add newlines after each sentence.
//
// Your goal is creating a new slice, then copying
// each sentence of the lyric to the new buffer, then
// after each sentence adding a newline character.
// So, create a new slice and copy every words into it. Lastly,
// after each sentence, add a newline character ('\n').
//
// You will get across something like this all the time
// in your gopher life. Believe me, learning how to
// solve this exercise will make you a better hopher.
// ORIGINAL SLICE:
// [yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday]
//
// EXPECTED SLICE (NEW):
// [yesterday all my troubles seemed so far \n away now it looks as though they are here to stay \n oh i believe in yesterday \n]
//
//
// RESTRICTIONS
//
// . For warming-up, in this exercise, never use the `append()` func.
//
// . Instead, only use the `copy()` func.
//
// . Don't use slicing for printing the sentences.
//
// . Instead, use slicing for filling the new buffer.
//
//
// STEPS
//
// . Please follow the instructions inside the code.
// CURRENT OUTPUT
//
// yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday
//
// EXPECTED OUTPUT
//
@ -49,79 +33,67 @@ import (
// now it looks as though they are here to stay
// oh i believe in yesterday
//
//
// RESTRICTIONS
//
// + Don't use `append()`, use `copy()` instead.
//
// + Don't cheat like this:
//
// fmt.Println(lyric[:8])
// fmt.Println(lyric[8:18])
// fmt.Println(lyric[18:23])
//
// + Create a new slice that contains the sentences
// with line endings.
//
//
// NOTE
//
// If the program does not work, please update your
// local copy of the prettyslice package:
//
// go get -u github.com/inancgumus/prettyslice
//
// ---------------------------------------------------------
func main() {
// You need to add a newline after each sentence in another slice.
// Don't touch the following code.
lyric := strings.Fields(`yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday`)
// ===================================
//
// ~~~ CHANGE THIS CODE ~~~
//
fix := lyric
//
// ===================================
// Currently, it prints every sentence on the same line.
// Don't touch the following code.
s.Show("fix slice", fix)
for _, w := range fix {
fmt.Print(w)
if w != "\n" {
fmt.Print(" ")
}
}
}
func init() {
//
// YOU DON'T NEED TO TOUCH THIS
//
// This inits some options for the prettyslice package.
// This initializes some options for the prettyslice package.
// You can change the options if you want.
//
// This code runs before the main function above.
//
// s.Colors(false) // if your editor is light background color then enable this
//
s.PrintBacking = true // prints the backing arrays
s.MaxPerLine = 15 // prints max 15 elements per line
s.SpaceCharacter = '*' // print this instead of printing a newline (for debugging)
//
// UNCOMMENT THE VARIABLE BELOW THEN START!
//
// lyric := strings.Fields(`yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday`)
//
// RESTRICTION EXPLANATION:
//
// Do not use slicing for printing the sentences.
//
// For example, don't do something like this:
//
// fmt.Println(lyric[:8])
// fmt.Println(lyric[8:18])
// fmt.Println(lyric[18:23])
// ========================================================================
//
// #1: CREATE A LARGE ENOUGH BUFFER (A NEW SLICE)
//
// You need to put each lyric sentence
// + a newline character into this buffer
//
// I name the buffer: `fix`, you can name it however you want
// fix := make(...)
// ========================================================================
//
// #2: CALCULATE THE CUT POINTS
//
// You want to put newlines after each sentence. So you may want to put
// these index positions into a slice. Then you can use them to cut the
// lyric slice.
//
// cutpoints := []int{...}
// ========================================================================
//
// #3: CREATE A LOOP AND COPY THE SENTENCES INTO THE BUFFER
//
// for ... {
// Use the `copy` function to copy from the `lyric` slice to the buffer.
//
// Copy a newline character (in a string) to the buffer after each sentence.
//
// You can use slicing here for filling the new buffer.
//
// Uncomment this to aid debugging (to see how the fix slice changes)
// s.Show("fix slice", fix)
// }
// ========================================================================
//
// #4: PRINT THE BUFFER
//
// ...
s.MaxPerLine = 5 // prints max 15 elements per line
s.SpaceCharacter = '⏎' // print this instead of printing a newline (for debugging)
}

93
16-slices/exercises/25-add-lines/solution/main.go
View File

@ -14,58 +14,45 @@ import (
s "github.com/inancgumus/prettyslice"
)
//
// ! NOTE If the program does not work, please update your
// local copy of the prettyslice package:
//
// go get -u github.com/inancgumus/prettyslice
//
func main() {
//
// YOU DON'T NEED TO TOUCH THIS
//
// This inits some options for the prettyslice package.
// You can change the options if you want.
//
// s.Colors(false) // if your editor is light colored then enable this
s.PrintBacking = true // prints the backing arrays
s.MaxPerLine = 15 // prints max 15 elements per line
s.SpaceCharacter = '⏎' // print this instead of printing a newline (for debugging)
lyric := strings.Fields(`yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday`)
// CREATE A LARGE ENOUGH BUFFER
// `+3` because we're going to add 3 newline characters
// `+3` because we're going to add 3 newline characters to the fix slice.
fix := make([]string, len(lyric)+3)
// CALCULATE THE CUT POINTS
//
// + The first sentence has 8 words so its cutpoint is 8.
// USE A SLICE TO STORE WHERE EACH SENTENCE ENDS
//
// + The second one has 10 words so its cutpoint is 10.
// + The first sentence has 8 words so its cutting index is 8.
//
// + The third one has 5 words so its cutpoint is 5.
// yesterday all my troubles seemed so far away now it looks as though they are here to stay
// |
// v
// cutting index: 8
//
//
// yesterday all my troubles seemed so far away now it looks as though they are here to stay
// |
// v
// cutpoint: 8
// + The second sentence has 10 words so its cutting index is 10.
//
// ... now it looks as though they are here to stay oh i believe in yesterday
// |
// v
// 10
// now it looks as though they are here to stay oh i believe in yesterday
// |
// v
// cutting index: 10
//
//
// + The last sentence has 5 words so its cutting index is 5.
//
// oh i believe in yesterday
// |
// v
// cutting index: 5
//
// ... now it looks as though they are here to stay oh i believe in yesterday
// |
// v
// 5
cutpoints := []int{8, 10, 5}
// `n` tracks how much we've moved inside the `lyric` slice
// `i` tracks the sentence that we're on
//
// `n` tracks how much we've moved inside the `lyric` slice.
//
// `i` tracks the sentence that we're on.
//
for i, n := 0, 0; n < len(lyric); i++ {
//
// copy to `fix` from the `lyric`
@ -81,16 +68,21 @@ func main() {
//
n += copy(fix[n+i:], lyric[n:n+cutpoints[i]])
// add a newline after the number of copied elements
// notice that the '\n' position slides as we move over
// that's why n+i
//
// add a newline after each sentence.
//
// notice that the '\n' position slides as we move over.
// that's why it's: `n+i`.
//
fix[n+i] = "\n"
// uncomment this to aid debugging (to see how the fix slice changes)
// uncomment to see how the fix slice changes.
// s.Show("fix slice", fix)
}
// print the fix slice
s.Show("fix slice", fix)
// print the sentences
for _, w := range fix {
fmt.Print(w)
if w != "\n" {
@ -98,3 +90,18 @@ func main() {
}
}
}
func init() {
//
// YOU DON'T NEED TO TOUCH THIS
//
// This initializes some options for the prettyslice package.
// You can change the options if you want.
//
// This code runs before the main function above.
//
// s.Colors(false) // if your editor is light background color then enable this
s.PrintBacking = true // prints the backing arrays
s.MaxPerLine = 5 // prints max 15 elements per line
s.SpaceCharacter = '⏎' // print this instead of printing a newline (for debugging)
}

2
16-slices/exercises/README.md
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@ -86,7 +86,7 @@ Please update your local copy of the prettyslice package for some examples to wo
A slice retrieved from an API causes a memory leak in your program. You need to fix it.
4. **[Add newlines to the lyric sentences](https://github.com/inancgumus/learngo/tree/master/16-slices/exercises/25-add-lines)**
4. **[Add a newline after each sentence](https://github.com/inancgumus/learngo/tree/master/16-slices/exercises/25-add-lines)**
Use the power of the `copy()` function and add newlines into a new buffer from a string slice. This exercise is more tricky than you might think.