added exercise 2 'string sorting'

.idea/Rust-Programming.iml

@@ -4,7 +4,9 @@
     <exclude-output />
     <content url="file://$MODULE_DIR$">
       <sourceFolder url="file://$MODULE_DIR$/duplicates/src" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/str_sort/src" isTestSource="false" />
       <excludeFolder url="file://$MODULE_DIR$/duplicates/target" />
+      <excludeFolder url="file://$MODULE_DIR$/str_sort/target" />
     </content>
     <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />

str_sort/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "str_sort"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

str_sort/src/main.rs

@@ -0,0 +1,80 @@
+/**
+ *                _ _   _               _
+ * __      ___ __(_) |_| |_ ___ _ __   | |__  _   _
+ * \ \ /\ / / '__| | __| __/ _ \ '_ \  | '_ \| | | |
+ *  \ V  V /| |  | | |_| ||  __/ | | | | |_) | |_| |
+ *   \_/\_/ |_|  |_|\__|\__\___|_| |_| |_.__/ \__, |
+ *                                            |___/
+ *  ____                  __     __               _
+ * / ___|_   _____ _ __   \ \   / /__   __ _  ___| |
+ * \___ \ \ / / _ \ '_ \   \ \ / / _ \ / _` |/ _ \ |
+ *  ___) \ V /  __/ | | |   \ V / (_) | (_| |  __/ |
+ * |____/ \_/ \___|_| |_|    \_/ \___/ \__, |\___|_|
+ *                                     |___/
+ * Licensed under the GPLv2 License, Version 2.0 (the "License");
+ * Copyright (c) Sven Vogel
+ */
+
+/// Sort the string chars alphabetically.
+/// This function works inplace but assumes the string to be ASCII only.
+/// If the supplied string is not exclusively ASCII the function will panic.
+/// The reason for this is that UTF-8 encoded string characters may take up more
+/// bytes than just one.
+fn sort_ascii_str_inplace(str: &mut String) {
+    if !str.is_ascii() {
+        panic!("String is not ascii")
+    }
+    unsafe {
+        str.as_mut_vec().sort();
+    }
+}
+
+/// Sort the input string alphabetically
+/// Works on any UTF-8 encoded string but requires N-bytes of extra allocated memory.
+fn sort_utf8_str_with_extra_mem(string: &mut String) {
+    let mut chars = string.chars().collect::<Vec<char>>();
+    chars.sort();
+    string.clear();
+    string.push_str(chars.into_iter().collect::<String>().as_str());
+}
+
+/// performs an inplace bubble sort on the supplied string
+fn sort_utf8_str_inplace(string: &mut String) {
+    let char_count = string.chars().count();
+
+    for x in 0..(char_count - 1) {
+        for y in 0..(char_count - x - 1) {
+            // we need to recalculate the correct character indices every time we changed sth.
+            let mut char_iter = string.char_indices();
+            // fetch character at index y and y + 1
+            let y0 = char_iter.nth(y).unwrap();
+            let y1 = char_iter.next().unwrap();
+
+            if y0.1 > y1.1 {
+                // replace character at y with the character from y + 1
+                string.remove(y0.0);
+                string.insert(y0.0, y1.1);
+
+                // replace character at y + 1 with the character from the original y
+                string.remove(y1.0);
+                string.insert(y1.0, y0.1);
+            }
+        }
+    }
+}
+
+fn main() {
+    const SOURCE: &'static str = "9876543210zyxwvutsrqponmlkjihgfedcba";
+
+    let mut to_sort = String::from(SOURCE);
+    sort_utf8_str_inplace(&mut to_sort);
+    println!("UTF-8 inplace: {to_sort}");
+
+    let mut to_sort = String::from(SOURCE);
+    sort_utf8_str_with_extra_mem(&mut to_sort);
+    println!("UTF-8 with extra memory: {to_sort}");
+
+    let mut to_sort = String::from(SOURCE);
+    sort_ascii_str_inplace(&mut to_sort);
+    println!("ASCII inplace + unsafe: {to_sort}");
+}