Palindrome initial import

[?]

Nov 29, 2020, 7:15 AM

MCHVA5DYOAOEBSHENAB4FYJBVE4A47B7GDDHOEM36BXTN63ZMQNAC

Dependencies

Change contents

file addition: snippets (dxwrxwrx-r)

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file addition: palindrome (dxwrxwrx-r)

[0.11]
file addition: palindrome.go (-xw-x--x--)

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// Palindrome is a string that is the same forward and backward

package main

import (
"bufio"
"fmt"
"os"
)

func main() {
scanner := bufio.NewScanner(os.Stdin)
for scanner.Scan() {
var str string
if len(scanner.Text()) > 2 {
str = palindrome(scanner.Text())
}
if len(str) > 2 {
fmt.Println(str)
}
}
if scanner.Err() != nil {
fmt.Fprintln(os.Stderr, "Error reading console input")
}
}

// Returns the longest palindrome in str
func palindrome(str string) string {
longest := ""
jobs := 0
results := make(chan string)
for k, _ := range str {
if k > 0 {
go pal_worker(str, k, results)
jobs++
}
}
for {
select {
case candidate := <-results:
jobs--
if len(candidate) > len(longest) {
longest = candidate
}
if jobs == 0 {
close(results)
return longest
}
}
}
}

func pal_worker(str string, k int, result chan<- string) {
longest := string(str[k])
for i := 1; true; i++ {
// avoid overrun or underrun
if k-i < 0 || k+i > len(str)-1 {
break
}
// two identical bytes
if str[k-i] == str[k+i] {
longest = string(str[k-i]) + longest + string(str[k+i])
} else {
break
}
}
//fmt.Fprintf(os.Stderr, "Worker(%d) result: %s\n", k, longest)
result <- longest
}
file addition: TODO.md (-xw-x--x--)

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# Couple of ideas

- make a note of these just to order them in my head
- write the basic version with no channels
- test channel closing methods: no more load, no more work, know number of
workers, unknown number of workers and loaders, channel buffer size based
channel closing?
- create separate channel for loader and worker
- measure (profile) loader and worker
- make suggestions: more loader or more worker is needed
- write tests for the functions