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Merge k sorted arrays in Rust
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// Blog post: https://creativcoder.dev/merge-k-sorted-arrays-rust | |
// Merge 2 sorted arrays | |
fn merge_2(a: &[i32], b: &[i32]) -> Vec<i32> { | |
let (mut i, mut j) = (0, 0); | |
let mut sorted = vec![]; | |
let remaining; | |
let remaining_idx; | |
loop { | |
if a[i] < b[j] { | |
sorted.push(a[i]); | |
i += 1; | |
if i == a.len() {remaining = b; remaining_idx = j; break;} | |
} else { | |
sorted.push(b[j]); | |
j += 1; | |
if j == b.len() {remaining = a; remaining_idx = i; break;} | |
} | |
} | |
for i in remaining_idx..remaining.len() { | |
sorted.push(remaining[i]); | |
} | |
sorted | |
} | |
// Merge k sorted arrays | |
#[derive(Debug, Eq)] | |
struct Item<'a> { | |
arr: &'a Vec<i32>, | |
idx: usize | |
} | |
impl<'a> PartialEq for Item<'a> { | |
fn eq(&self, other: &Self) -> bool { | |
self.get_item() == other.get_item() | |
} | |
} | |
impl<'a> PartialOrd for Item<'a> { | |
fn partial_cmp(&self, other: &Self) -> Option<Ordering> { | |
self.get_item().partial_cmp(&other.get_item()) | |
} | |
} | |
impl<'a> Ord for Item<'a> { | |
fn cmp(&self, other: &Self) -> Ordering { | |
self.get_item().cmp(&other.get_item()) | |
} | |
} | |
impl<'a> Item<'a> { | |
fn new(arr: &'a Vec<i32>, idx: usize) -> Self { | |
Self { | |
arr, | |
idx | |
} | |
} | |
fn get_item(&self) -> i32 { | |
self.arr[self.idx] | |
} | |
} | |
use std::collections::BinaryHeap; | |
use std::cmp::Reverse; | |
use std::cmp::Ordering; | |
fn merge(arrays: Vec<Vec<i32>>) -> Vec<i32> { | |
let mut sorted = vec![]; | |
let mut heap = BinaryHeap::with_capacity(arrays.len()); | |
for arr in &arrays { | |
let item = Item::new(arr, 0); | |
heap.push(Reverse(item)); | |
} | |
while !heap.is_empty() { | |
let mut it = heap.pop().unwrap(); | |
sorted.push(it.0.get_item()); | |
it.0.idx += 1; | |
if it.0.idx < it.0.arr.len() { | |
heap.push(it) | |
} | |
} | |
sorted | |
} | |
fn main() { | |
let a = vec![1, 5, 7]; | |
let b = vec![-2, 3, 4]; | |
let v = vec![a, b]; | |
dbg!(merge(v)); | |
} |
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Would you care to state a license for this code? I would welcome MIT 👌