09-bubble_sort.zig

const std = @import("std");
const print = std.debug.print;
const time = std.time;
const Timestamp = std.Io.Timestamp;
const allocator = std.heap.page_allocator;
const Random = std.Random;
const mem = std.mem;

/// Function to perform Bubble Sort on an array.
///
/// # Parameters
///
/// - `arr`: The array to sort.
fn bubbleSort(arr: []usize) void {
    const n = arr.len;
    for (0..n - 1) |i| {
        for (0..(n - i - 1)) |j| {
            if (arr[j] > arr[j + 1]) {
                // Swap arr[j] and arr[j + 1]
                mem.swap(usize, &arr[j], &arr[j + 1]);
            }
        }
    }
}

/// Function to verify if an array is sorted.
///
/// # Parameters
///
/// - `arr`: The array to check.
fn isSorted(arr: []usize) bool {
    const n = arr.len;
    for (0..n - 1) |i| {
        if (arr[i] > arr[i + 1]) {
            return false;
        }
    }
    return true;
}

/// Main function to demonstrate Bubble Sort and measure execution time.
pub fn main(init: std.process.Init) !void {
    const io = init.io;
    const N_values = [_]usize{ 10_000, 20_000, 30_000, 40_000 };

    // Seed the random number generator
    var rng = Random.DefaultPrng.init(123); // Xoshiro256 is good enough

    for (N_values) |N| {
        // Allocate memory for the array
        var arr = try allocator.alloc(usize, N);
        defer allocator.free(arr);

        // Fill the array with random integers
        for (0..N) |i| {
            const random_value: usize = rng.next() % N;
            arr[i] = random_value;
        }

        // Measure the start time
        const start = Timestamp.now(io, .awake);

        // Perform Bubble Sort
        bubbleSort(arr);

        // Measure the end time
        const end = Timestamp.now(io, .awake);

        // Calculate the elapsed time in seconds
        const elapsed: f64 = @floatFromInt(end.nanoseconds - start.nanoseconds);
        const time_spent = elapsed / time.ns_per_s;

        // Verify that the array is sorted
        const is_sorted = isSorted(arr);

        // Print the result and time
        print("Bubble Sort with N = {d}\n", .{N});
        if (is_sorted) {
            print("Array is sorted.\n", .{});
        } else {
            print("Array is NOT sorted.\n", .{});
        }
        print("Time taken: {d} seconds\n\n", .{time_spent});
    }
}