Added word pattern solution.

README.md

@@ -169,6 +169,7 @@ programming challenges completed in other languages.
 - [Count Negative Numbers](https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix)
 - [Guess Number](https://leetcode.com/problems/guess-number-higher-or-lower/)
 - [Ransom Note](https://leetcode.com/problems/ransom-note)
+- [Word Pattern](https://leetcode.com/problems/word-pattern)
 
 #### Medium
 

src/leetcode/mod.rs

@@ -157,6 +157,7 @@ mod unguarded_cells;
 mod unique_occurrences;
 mod valid_parenthesis;
 mod valid_sudoku;
+mod word_pattern;
 mod x_kind;
 mod xor_subarray;
 mod zero_or_one;

src/leetcode/word_pattern.rs

@@ -0,0 +1,37 @@
+use std::collections::HashMap;
+
+pub fn word_pattern(pattern: String, s: String) -> bool {
+    let words: Vec<_> = s.split_whitespace().map(String::from).collect();
+    if pattern.len() != words.len() {
+        return false;
+    }
+
+    let pattern = pattern.as_bytes();
+    let mut map = HashMap::new();
+    for (i, word) in words.into_iter().enumerate() {
+        if map.insert(pattern[i].to_string(), i) != map.insert(word, i) {
+            return false;
+        }
+    }
+    true
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        assert!(word_pattern("aaa".to_string(), "dog dog dog".to_string()))
+    }
+
+    #[test]
+    fn test_name() {
+        assert!(!word_pattern("aaa".to_string(), "dog cat dog".to_string()));
+        assert!(!word_pattern(
+            "abba".to_string(),
+            "dog dog dog dog".to_string()
+        ));
+        assert!(!word_pattern("aaa".to_string(), "aa aa aa aa".to_string()))
+    }
+}