v/examples/quick_sort.v

43 lines
971 B
V

import rand
const (
gen_len = 1000 // how many random numbers to generate
gen_max = 10000 // max of the generated numbers
)
fn main() {
mut arr := []int{}
for _ in 0 .. gen_len {
arr << rand.intn(gen_max) or { 0 }
}
println('length of random array is $arr.len')
println('before quick sort whether array is sorted: ${is_sorted<int>(arr)}')
quick_sort<int>(mut arr, 0, arr.len - 1)
println('after quick sort whether array is sorted: ${is_sorted<int>(arr)}')
}
fn quick_sort<T>(mut arr []T, l int, r int) {
if l >= r {
return
}
mut sep := l // what is sep: [...all_value<arr[sep]...sep...all_value>=arr[sep]...]
for i in l + 1 .. r + 1 {
if arr[i] < arr[l] {
sep++
arr[i], arr[sep] = arr[sep], arr[i]
}
}
arr[l], arr[sep] = arr[sep], arr[l]
quick_sort<T>(mut arr, l, sep - 1)
quick_sort<T>(mut arr, sep + 1, r)
}
fn is_sorted<T>(arr []T) bool {
for i in 0 .. arr.len - 1 {
if arr[i] > arr[i + 1] {
return false
}
}
return true
}