2185. Counting Words With a Given Prefix: AC

Author: tan-wei

src/solution/mod.rs

@@ -1651,3 +1651,4 @@ mod s2180_count_integers_with_even_digit_sum;
 mod s2181_merge_nodes_in_between_zeros;
 mod s2182_construct_string_with_repeat_limit;
 mod s2183_count_array_pairs_divisible_by_k;
+mod s2185_counting_words_with_a_given_prefix;

src/solution/s2185_counting_words_with_a_given_prefix.rs

@@ -0,0 +1,72 @@
+/**
+ * [2185] Counting Words With a Given Prefix
+ *
+ * You are given an array of strings words and a string pref.
+ * Return the number of strings in words that contain pref as a prefix.
+ * A prefix of a string s is any leading contiguous substring of s.
+ *  
+ * Example 1:
+ *
+ * Input: words = ["pay","<u>at</u>tention","practice","<u>at</u>tend"], pref = "at"
+ * Output: 2
+ * Explanation: The 2 strings that contain "at" as a prefix are: "<u>at</u>tention" and "<u>at</u>tend".
+ *
+ * Example 2:
+ *
+ * Input: words = ["leetcode","win","loops","success"], pref = "code"
+ * Output: 0
+ * Explanation: There are no strings that contain "code" as a prefix.
+ *
+ *  
+ * Constraints:
+ *
+ * 	1 <= words.length <= 100
+ * 	1 <= words[i].length, pref.length <= 100
+ * 	words[i] and pref consist of lowercase English letters.
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/counting-words-with-a-given-prefix/
+// discuss: https://leetcode.com/problems/counting-words-with-a-given-prefix/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn prefix_count(words: Vec<String>, pref: String) -> i32 {
+        words.into_iter().fold(0, |s, w| {
+            s + if pref.len() <= w.len() && w.chars().zip(pref.chars()).all(|(c1, c2)| c1 == c2) {
+                1
+            } else {
+                0
+            }
+        })
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2185_example_1() {
+        let words = vec_string!["pay", "attention", "practice", "attend"];
+        let pref = "at".to_string();
+
+        let result = 2;
+
+        assert_eq!(Solution::prefix_count(words, pref), result);
+    }
+
+    #[test]
+    fn test_2185_example_2() {
+        let words = vec_string!["leetcode", "win", "loops", "success"];
+        let pref = "code".to_string();
+
+        let result = 0;
+
+        assert_eq!(Solution::prefix_count(words, pref), result);
+    }
+}