robert: Add sort compare

robert/Cargo.toml

@@ -5,4 +5,5 @@ edition = "2021"
 publish = false
 
 [dependencies]
+rand = "0.8.5"
 sorts = { path = "../sorts" }

robert/src/bin/sort_compare.rs

@@ -0,0 +1,54 @@
+// Copyright (c) 2020 Xu Shaohua <[email protected]>. All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+use rand::Rng;
+use std::time::Instant;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum Variant {
+    InsertionSort,
+    SelectionSort,
+    ShellSort,
+}
+
+fn time_sort(array: &mut [f64], variant: Variant) -> u128 {
+    let instance = Instant::now();
+    match variant {
+        Variant::InsertionSort => sorts::insertion_sort(array),
+        Variant::SelectionSort => sorts::selection_sort(array),
+        Variant::ShellSort => sorts::shell_sort(array),
+    }
+    return instance.elapsed().as_nanos();
+}
+
+fn time_random_input(variant: Variant, len: usize, times: i32) -> u128 {
+    let mut total = 0;
+    let mut rng = rand::thread_rng();
+    let mut array = vec![0.0; len];
+    for _t in 0..times {
+        for i in 0..len {
+            array[i] = rng.gen();
+        }
+        total += time_sort(&mut array, variant);
+    }
+
+    return total;
+}
+
+fn main() {
+    let args: Vec<String> = std::env::args().collect();
+    if args.len() != 3 {
+        panic!("Usage: number times");
+    }
+    let num: usize = args[1].parse().expect("Invalid total length");
+    let times: i32 = args[2].parse().expect("Invalid times");
+    let t1 = time_random_input(Variant::InsertionSort, num, times);
+    let t2 = time_random_input(Variant::SelectionSort, num, times);
+    let t3 = time_random_input(Variant::ShellSort, num, times);
+
+    println!("Insertion: {t1}, Selection: {t2}, ShellSort: {t3}");
+    let ratio1: f64 = (t1 as f64) / (t3 as f64);
+    let ratio2: f64 = t2 as f64 / t3 as f64;
+    println!("Insertion ratio: {ratio1:.2}, Selection ratio: {ratio2:.2}, Shell ratio: 1.0");
+}