Update README.md

Author: Yonghee9106

README.md

@@ -9,4 +9,4 @@
 | 5 | [Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring/) | [Java](https://github.com/Yonghee9106/leetcode-solutions/blob/main/Java/0005_Longest_Palindromic_Substring.java), [JavaScript](https://github.com/Yonghee9106/leetcode-solutions/blob/main/JavaScript/0005_Longest_Palindromic_Substring.js), [Python](https://github.com/Yonghee9106/leetcode-solutions/blob/main/Python/0005_Longest_Palindromic_Substring.py) | Medium | $O(n^2)$ |
 | 6 | [Zigzag Conversion](https://leetcode.com/problems/zigzag-conversion/) | [Java](https://github.com/Yonghee9106/leetcode-solutions/blob/main/Java/0006_Zigzag_Conversion.java), [JavaScript](https://github.com/Yonghee9106/leetcode-solutions/blob/main/JavaScript/0006_Zigzag_Conversion.js), [Python](https://github.com/Yonghee9106/leetcode-solutions/blob/main/Python/0006_Zigzag_Conversion.py) | Medium | $O(n)$ |
 | 7 | [Reverse Integer](https://leetcode.com/problems/reverse-integer/) | [Java](https://github.com/Yonghee9106/leetcode-solutions/blob/main/Java/0007_Reverse_Integer.java), [JavaScript](https://github.com/Yonghee9106/leetcode-solutions/blob/main/JavaScript/0007_Reverse_Integer.js), [Python](https://github.com/Yonghee9106/leetcode-solutions/blob/main/Python/0007_Reverse_Integer.py) | Medium | $O(log(x))$ |
-| 8 | | | | |
+| 8 | [String to Integer (atoi)](https://leetcode.com/problems/string-to-integer-atoi/) | | Medium | |