Add problem 0520: Detect Capital

src/lib.rs

@@ -351,6 +351,7 @@ pub mod problem_0504_base_7;
 pub mod problem_0507_perfect_number;
 pub mod problem_0513_find_bottom_left_tree_value;
 pub mod problem_0515_find_largest_value_in_each_tree_row;
+pub mod problem_0520_detect_capital;
 pub mod problem_0523_continuous_subarray_sum;
 pub mod problem_0525_contiguous_array;
 pub mod problem_0530_minimum_absolute_difference_in_bst;

src/problem_0520_detect_capital/iterative.rs

@@ -0,0 +1,33 @@
+pub struct Solution;
+
+impl Solution {
+    pub fn detect_capital_use(word: String) -> bool {
+        let mut iter = word.chars();
+        let first = iter.next().unwrap();
+        if first.is_ascii_uppercase() {
+            iter.next().map_or(true, |n| {
+                if n.is_ascii_uppercase() {
+                    iter.all(|x| x.is_ascii_uppercase())
+                } else {
+                    iter.all(|x| x.is_ascii_lowercase())
+                }
+            })
+        } else {
+            iter.all(|x| x.is_ascii_lowercase())
+        }
+    }
+}
+
+impl super::Solution for Solution {
+    fn detect_capital_use(word: String) -> bool {
+        Self::detect_capital_use(word)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_0520_detect_capital/mod.rs

@@ -0,0 +1,36 @@
+pub mod iterative;
+pub mod pattern_matching;
+
+pub trait Solution {
+    fn detect_capital_use(word: String) -> bool;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            ("USA", true),
+            ("FlaG", false),
+            ("U", true),
+            ("u", true),
+            ("US", true),
+            ("Us", true),
+            ("uS", false),
+            ("us", true),
+            ("USB", true),
+            ("USb", false),
+            ("UsB", false),
+            ("Usb", true),
+            ("uSB", false),
+            ("uSb", false),
+            ("usB", false),
+            ("usb", true),
+        ];
+
+        for (word, expected) in test_cases {
+            assert_eq!(S::detect_capital_use(word.to_string()), expected);
+        }
+    }
+}

src/problem_0520_detect_capital/pattern_matching.rs

@@ -0,0 +1,26 @@
+pub struct Solution;
+
+impl Solution {
+    pub fn detect_capital_use(word: String) -> bool {
+        match word.as_bytes() {
+            [_] => true,
+            [b'A'..=b'Z', b'A'..=b'Z', rest @ ..] => rest.iter().all(u8::is_ascii_uppercase),
+            [b'A'..=b'Z', b'a'..=b'z', rest @ ..] => rest.iter().all(u8::is_ascii_lowercase),
+            word => word.iter().all(u8::is_ascii_lowercase),
+        }
+    }
+}
+
+impl super::Solution for Solution {
+    fn detect_capital_use(word: String) -> bool {
+        Self::detect_capital_use(word)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}