20240422 Finished

src/problem/mod.rs

@@ -109,3 +109,4 @@ mod p135_candy;
 mod p42_trapping_rain_water;
 mod p58_length_of_last_word;
 mod p151_reverse_words_in_a_string;
+mod p28_find_the_index_of_the_first_occurrence_in_a_string;

src/problem/p28_find_the_index_of_the_first_occurrence_in_a_string.rs

@@ -0,0 +1,27 @@
+/**
+ * [28] Find the Index of the First Occurrence in a String
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+
+impl Solution {
+    pub fn str_str(haystack: String, needle: String) -> i32 {
+        match haystack.find(&needle)  {
+            Some(pos) => pos as i32,
+            None => -1   
+        }
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_28() {
+    }
+}