Data commit

Task/Longest-string-challenge/Rust/longest-string-challenge.rust

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+use std::cmp::Ordering;
+use std::io::BufRead;
+
+/// Compares the length of two strings by iterating over their characters
+/// together until either string has run out.
+fn compare(a: &str, b: &str) -> Ordering {
+    let mut a = a.chars();
+    let mut b = b.chars();
+    loop {
+        match (a.next(), b.next()) {
+            (None, None) => return Ordering::Equal,
+            (Some(_), None) => return Ordering::Greater,
+            (None, Some(_)) => return Ordering::Less,
+            (Some(_), Some(_)) => {}
+        }
+    }
+}
+
+/// Returns the longest lines of the input, separated by newlines.
+fn longest<I: IntoIterator<Item = String>>(input: I) -> String {
+    let mut longest = String::new();
+    let mut output = String::new();
+
+    for line in input {
+        match compare(&line, &longest) {
+            // A longer string replaces the output and longest.
+            Ordering::Greater => {
+                output.clear();
+                output.push_str(&line);
+                longest = line;
+            }
+            // A string of the same length is appended to the output.
+            Ordering::Equal => {
+                output.push('\n');
+                output.push_str(&line);
+            }
+            // A shorter string is ignored.
+            Ordering::Less => {}
+        }
+    }
+
+    output
+}
+
+fn main() {
+    let stdin = std::io::stdin();
+    let lines = stdin.lock().lines().map(|l| l.expect("Failed to read."));
+
+    println!("{}", longest(lines))
+}