feat: init Find the Index of the First Occurrence in a String

Author: bujosa

src/easy/find_the_index_of_the_first_occurrence_in_a_string.rs

@@ -0,0 +1,36 @@
+#[allow(dead_code)]
+pub fn str_str(haystack: String, needle: String) -> i32 {
+    let haystack = haystack.as_bytes();
+    let needle = needle.as_bytes();
+
+    if needle.len() == 0 {
+        return 0;
+    }
+
+    let mut i = 0;
+    let mut j = 0;
+
+    while i < haystack.len() {
+        if haystack[i] == needle[j] {
+            i += 1;
+            j += 1;
+            if j == needle.len() {
+                return (i - j) as i32;
+            }
+        } else {
+            i = i - j + 1;
+            j = 0;
+        }
+    }
+    -1
+}
+
+
+#[test]
+fn test_str_str() {
+    assert_eq!(str_str("hello".to_string(), "ll".to_string()), 2);
+    assert_eq!(str_str("aaaaa".to_string(), "bba".to_string()), -1);
+    assert_eq!(str_str("".to_string(), "".to_string()), 0);
+    assert_eq!(str_str("a".to_string(), "".to_string()), 0);
+    assert_eq!(str_str("".to_string(), "a".to_string()), -1);
+}

src/easy/mod.rs

@@ -1,3 +1,4 @@
+pub mod find_the_index_of_the_first_occurrence_in_a_string;
 pub mod longest_common_prefix;
 pub mod merged_two_sorted_lists;
 pub mod palindrome_linked_list;

src/easy/two_sum.rs

@@ -1,3 +1,4 @@
+#![allow(dead_code)]
 use std::collections::HashMap;
 
 pub fn two_sum(nums: Vec<i32>, target: i32) -> Vec<i32> {