Implement strStr()

Author: Kilerd

src/implement_strstr.rs

@@ -0,0 +1,77 @@
+/// @number 28
+/// @title Implement strStr()
+/// @url https://leetcode.com/problems/implement-strstr/
+/// @difficulty easy
+
+
+struct Solution;
+
+impl Solution {
+    pub fn str_str(haystack: String, needle: String) -> i32 {
+        let haystack_len = haystack.len();
+        let needle_len = needle.len();
+
+        if needle_len == 0 { return 0; }
+
+        let mut i = 0;
+        'main: while (i as i32) <= (haystack_len as i32 - needle_len as i32) {
+            let mut j = 0;
+            if !&haystack[i..i + 1].eq(&needle[j..j + 1]) {
+                i += 1;
+                continue;
+            }
+            let mut k = i;
+            while j < needle_len {
+                if !&haystack[k..k + 1].eq(&needle[j..j + 1]) {
+                    i += 1;
+                    continue 'main;
+                }
+                k += 1;
+                j += 1;
+            }
+            return i as i32;
+        }
+        -1
+    }
+}
+
+
+#[cfg(test)]
+mod test {
+    use crate::implement_strstr::Solution;
+
+    #[test]
+    fn test1() {
+        assert_eq!(2, Solution::str_str("hello".into(), "ll".into()));
+    }
+
+    #[test]
+    fn test2() {
+        assert_eq!(-1, Solution::str_str("aaaaa".into(), "-1".into()));
+    }
+
+    #[test]
+    fn test3() {
+        assert_eq!(0, Solution::str_str("aaaaa".into(), "".into()));
+    }
+
+    #[test]
+    fn test4() {
+        assert_eq!(-1, Solution::str_str("".into(), "a".into()));
+    }
+
+    #[test]
+    fn test5() {
+        assert_eq!(-1, Solution::str_str("aaaa".into(), "aaaaa".into()));
+    }
+
+    #[test]
+    fn test6() {
+        assert_eq!(0, Solution::str_str("a".into(), "a".into()));
+    }
+
+    #[test]
+    fn test7() {
+        assert_eq!(4, Solution::str_str("mississippi".into(), "issip".into()));
+    }
+}

src/main.rs

@@ -31,4 +31,5 @@ mod three_sum_closest;
 mod letter_combinations_of_a_phone_number;
 mod valid_parentheses;
 mod remove_duplicates_from_sorted_array;
-mod remove_element;
+mod remove_element;
+mod implement_strstr;