Add longest_palindrome

Author: martwz

src/leetcode/top_interview/array_and_string/longest_palindrome.rs

@@ -0,0 +1,63 @@
+// 5. Longest Palindromic Substring, Medium
+// https://leetcode.com/problems/longest-palindromic-substring/
+impl Solution {
+    pub fn longest_palindrome(s: String) -> String {
+        let n = s.len();
+        if n <= 1 {
+            return s;
+        }
+
+        let chars = s.chars().collect::<Vec<char>>();
+
+        let mut ans = chars[0].to_string();
+        let mut dp = vec![vec![false; n]; n];
+        for i in 0..n {
+            dp[i][i] = true;
+        }
+
+        let mut max_len = 0;
+        for end in 1..n {
+            for start in 0..end {
+                if chars[start] == chars[end] {
+                    if end - start == 1 || dp[start + 1][end - 1] {
+                        dp[start][end] = true;
+                        if max_len < end - start + 1 {
+                            max_len = end - start + 1;
+                            ans = chars[start..=end].iter().collect::<String>();
+                        }
+                    }
+                }
+            }
+        }
+
+        return ans;
+    }
+}
+
+struct Solution {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{vec_string, vec_vec_i32, vec_vec_string};
+
+    #[test]
+    fn test_longest_palindrome() {
+        assert_eq!(Solution::longest_palindrome("babad".to_string()), "bab".to_string());
+    }
+
+    #[test]
+    fn test_longest_palindrome2() {
+        assert_eq!(Solution::longest_palindrome("cbbd".to_string()), "bb".to_string());
+    }
+
+    #[test]
+    fn test_longest_palindrome3() {
+        assert_eq!(Solution::longest_palindrome("a".to_string()), "a".to_string());
+    }
+
+    #[test]
+    fn test_longest_palindrome4() {
+        assert_eq!(Solution::longest_palindrome("ac".to_string()), "a".to_string());
+    }
+}

src/leetcode/top_interview/array_and_string/mod.rs

@@ -1,4 +1,5 @@
 mod group_anagrams;
 mod increasing_triplet;
 mod length_of_longest_substring;
-mod set_zeroes;
+mod longest_palindrome;
+mod set_zeroes;