686. Repeated String Match: AC

Author: tan-wei

src/solution/mod.rs

@@ -497,3 +497,4 @@ mod s0680_valid_palindrome_ii;
 mod s0682_baseball_game;
 mod s0684_redundant_connection;
 mod s0685_redundant_connection_ii;
+mod s0686_repeated_string_match;

src/solution/s0686_repeated_string_match.rs

@@ -0,0 +1,68 @@
+/**
+ * [0686] Repeated String Match
+ *
+ * Given two strings a and b, return the minimum number of times you should repeat string a so that string b is a substring of it. If it is impossible for b​​​​​​ to be a substring of a after repeating it, return -1.
+ * Notice: string "abc" repeated 0 times is "", repeated 1 time is "abc" and repeated 2 times is "abcabc".
+ *  
+ * Example 1:
+ *
+ * Input: a = "abcd", b = "cdabcdab"
+ * Output: 3
+ * Explanation: We return 3 because by repeating a three times "abcdabcdabcd", b is a substring of it.
+ *
+ * Example 2:
+ *
+ * Input: a = "a", b = "aa"
+ * Output: 2
+ *
+ *  
+ * Constraints:
+ *
+ * 	1 <= a.length, b.length <= 10^4
+ * 	a and b consist of lowercase English letters.
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/repeated-string-match/
+// discuss: https://leetcode.com/problems/repeated-string-match/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn repeated_string_match(a: String, b: String) -> i32 {
+        let mut c = String::new();
+        for i in 0..(b.len() / a.len() + 3) {
+            if c.contains(&b) {
+                return i as i32;
+            }
+            c = format!("{}{}", c, a);
+        }
+        -1
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_0686_example_1() {
+        let a = "abcd".to_string();
+        let b = "cdabcdab".to_string();
+        let result = 3;
+
+        assert_eq!(Solution::repeated_string_match(a, b), result);
+    }
+
+    #[test]
+    fn test_0686_example_2() {
+        let a = "a".to_string();
+        let b = "aa".to_string();
+        let result = 2;
+
+        assert_eq!(Solution::repeated_string_match(a, b), result);
+    }
+}