Data update

Task/Stem-and-leaf-plot/Rust/stem-and-leaf-plot.rs

@@ -0,0 +1,120 @@
+//  ================================================================                          :
+// Advice: Rust with a functional approach
+//       : Treats single-digit numbers as having a leading zero (stem 0)
+//       : Uses the last digit as the leaf
+//       : Includes all stems from 0 to 14
+//       : Uses a functional approach with pure functions
+//       : Produces monospaced plain text output
+//  ================================================================
+
+use std::collections::BTreeMap;
+
+// ================================================================
+//  Mathematical Helper Functions (Pure)
+// ================================================================
+
+// Conceptually expands single digit numbers.
+// Numerically unchanged, included for semantic clarity.
+fn expand_number(n: u32) -> u32 {
+    n
+}
+
+// Returns the stem (all but the last digit).
+// Example: 127 -> 12
+fn stem(n: u32) -> u32 {
+    n / 10
+}
+
+// Returns the leaf (last digit).
+// Example: 127 -> 7
+fn leaf(n: u32) -> u32 {
+    n % 10
+}
+
+// ================================================================
+//  Data Transformation Layer (Pure Functional Pipeline)
+// ================================================================
+
+// Builds the stem-leaf structure.
+// Returns a BTreeMap so stems are automatically sorted.
+// Ensures stems 0..14 always exist.
+fn build_stem_leaf(data: &[u32]) -> BTreeMap<u32, Vec<u32>> {
+    // Step 1: Expand and sort the data
+    let mut sorted: Vec<u32> = data.iter().map(|&n| expand_number(n)).collect();
+
+    sorted.sort();
+
+    // Step 2: Create all stems 0..14
+    (0..=14)
+        .map(|s| {
+            // Collect and sort leaves belonging to this stem
+            let mut leaves: Vec<u32> = sorted
+                .iter()
+                .filter(|&&n| stem(n) == s)
+                .map(|&n| leaf(n))
+                .collect();
+
+            leaves.sort();
+
+            (s, leaves)
+        })
+        .collect()
+}
+
+// ================================================================
+//  Formatting Layer (Pure Rendering)
+// ================================================================
+
+// Formats a stem as two digits (leading zero if necessary).
+// Example: 7 -> "07"
+fn format_stem(s: u32) -> String {
+    format!("{:02}", s)
+}
+
+// Formats leaves as space-separated digits.
+// Example: [1,3,7] -> "1 3 7"
+fn format_leaves(leaves: &[u32]) -> String {
+    leaves
+        .iter()
+        .map(|l| l.to_string())
+        .collect::<Vec<String>>()
+        .join(" ")
+}
+
+// Renders the complete stem-and-leaf plot as multi-line string.
+fn render_plot(stem_leaf: &BTreeMap<u32, Vec<u32>>) -> String {
+    stem_leaf
+        .iter()
+        .map(|(s, leaves)| format!("{} | {}", format_stem(*s), format_leaves(leaves)))
+        .collect::<Vec<String>>()
+        .join("\n")
+}
+
+// ================================================================
+//  Program Entry Point
+// ================================================================
+
+fn main() {
+    // ------------------------------------------------------------
+    // Raw Dataset
+    // ------------------------------------------------------------
+    let data: Vec<u32> = vec![
+        12, 127, 28, 42, 39, 113, 42, 18, 44, 118, 44, 37, 113, 124, 37, 48, 127, 36, 29, 31, 125,
+        139, 131, 115, 105, 132, 104, 123, 35, 113, 122, 42, 117, 119, 58, 109, 23, 105, 63, 27,
+        44, 105, 99, 41, 128, 121, 116, 125, 32, 61, 37, 127, 29, 113, 121, 58, 114, 126, 53, 114,
+        96, 25, 109, 7, 31, 141, 46, 13, 27, 43, 117, 116, 27, 7, 68, 40, 31, 115, 124, 42, 128,
+        52, 71, 118, 117, 38, 27, 106, 33, 117, 116, 111, 40, 119, 47, 105, 57, 122, 109, 124, 115,
+        43, 120, 43, 27, 27, 18, 28, 48, 125, 107, 114, 34, 133, 45, 120, 30, 127, 31, 116, 146,
+    ];
+
+    // ------------------------------------------------------------
+    // Functional Processing Pipeline
+    // ------------------------------------------------------------
+    let stem_leaf_structure = build_stem_leaf(&data);
+    let plot = render_plot(&stem_leaf_structure);
+
+    // ------------------------------------------------------------
+    // Output (Monospaced Plain Text)
+    // ------------------------------------------------------------
+    println!("{}", plot);
+}