LC 2490. Circular Sentence (Rust)

Author: raul-sauco

README.md

@@ -720,6 +720,7 @@ to the solution in this repository.
 | [2481. Minimum Cuts to Divide a Circle][lc2481]                                               | 🟢 Easy    | [![python](res/py.png)][lc2481py]                                                                     |
 | [2485. Find the Pivot Integer][lc2485]                                                        | 🟢 Easy    | [![rust](res/rs.png)][lc2485rs]                                                                       |
 | [2486. Append Characters to String to Make Subsequence][lc2486]                               | 🟠 Medium  | [![rust](res/rs.png)][lc2486rs]                                                                       |
+| [2490. Circular Sentence][lc2490]                                                             | 🟢 Easy    | [![rust](res/rs.png)][lc2490rs]                                                                       |
 | [2491. Divide Players Into Teams of Equal Skill][lc2491]                                      | 🟠 Medium  | [![rust](res/rs.png)][lc2491rs]                                                                       |
 | [2492. Minimum Score of a Path Between Two Cities][lc2492]                                    | 🟠 Medium  | [![python](res/py.png)][lc2492py] [![rust](res/rs.png)][lc2492rs]                                     |
 | [2501. Longest Square Streak in an Array][lc2501]                                             | 🟠 Medium  | [![rust](res/rs.png)][lc2501rs]                                                                       |
@@ -2368,6 +2369,8 @@ to the solution in this repository.
 [lc2485rs]: leetcode/find-the-pivot-integer.rs
 [lc2486]: https://leetcode.com/problems/append-characters-to-string-to-make-subsequence/
 [lc2486rs]: leetcode/append-characters-to-string-to-make-subsequence.rs
+[lc2490]: https://leetcode.com/problems/circular-sentence/
+[lc2490rs]: leetcode/circular-sentence.rs
 [lc2491]: https://leetcode.com/problems/divide-players-into-teams-of-equal-skill/
 [lc2491rs]: leetcode/divide-players-into-teams-of-equal-skill.rs
 [lc2492]: https://leetcode.com/problems/minimum-score-of-a-path-between-two-cities/

leetcode/circular-sentence.rs

@@ -0,0 +1,70 @@
+// 2490. Circular Sentence
+// 🟢 Easy
+//
+// https://leetcode.com/problems/circular-sentence/
+//
+// Tags: String
+
+struct Solution;
+impl Solution {
+    /// Save the first char in the input, then iterate over the chars in the input checking that
+    /// the chars before and after blank spaces match, if any of them do not, return false,
+    /// otherwise return first == last.
+    ///
+    /// Time complexity: O(n) - We may visit all chars in the input.
+    /// Space complexity: O(1) - We store two chars and one bool.
+    ///
+    /// Runtime 0 ms Beats 100%
+    /// Memory 2.16 MB Beats 50%
+    pub fn is_circular_sentence(sentence: String) -> bool {
+        let first = sentence.chars().next().expect("A first char");
+        let (mut last, mut after_blank) = (first, false);
+        for c in sentence.chars() {
+            match c {
+                ' ' => after_blank = true,
+                _ => {
+                    if after_blank && c != last {
+                        return false;
+                    }
+                    after_blank = false;
+                    last = c;
+                }
+            }
+        }
+        first == last
+    }
+}
+
+// Tests.
+fn main() {
+    let tests = [
+        ("leetcode exercises sound delightful", true),
+        ("eetcode", true),
+        ("Leetcode is cool", false),
+    ];
+    println!("\n\x1b[92m» Running {} tests...\x1b[0m", tests.len());
+    let mut success = 0;
+    for (i, t) in tests.iter().enumerate() {
+        let res = Solution::is_circular_sentence(t.0.to_owned());
+        if res == t.1 {
+            success += 1;
+            println!("\x1b[92m✔\x1b[95m Test {} passed!\x1b[0m", i);
+        } else {
+            println!(
+                "\x1b[31mx\x1b[95m Test {} failed expected: {:?} but got {}!!\x1b[0m",
+                i, t.1, res
+            );
+        }
+    }
+    println!();
+    if success == tests.len() {
+        println!("\x1b[30;42m✔ All tests passed!\x1b[0m")
+    } else if success == 0 {
+        println!("\x1b[31mx \x1b[41;37mAll tests failed!\x1b[0m")
+    } else {
+        println!(
+            "\x1b[31mx\x1b[95m {} tests failed!\x1b[0m",
+            tests.len() - success
+        )
+    }
+}