Longest palindromic substring dp (#12)

* add SolutionImplDP

* impl SolutionImplDP

* fix clippy

leetcode/src/solutions/longest_palindromic_substring.rs

@@ -1,6 +1,8 @@
 use super::Solution;
 use std::collections::HashMap;
 
+const TEST_CASES: [(&str, &str); 3] = [("babad", "bab"), ("cbbd", "bb"), ("aaaaa", "aaaaa")];
+
 pub struct SolutionImpl;
 
 impl Solution for SolutionImpl {
@@ -14,9 +16,7 @@ impl Solution for SolutionImpl {
         crate::location!()
     }
     fn test(&self) -> anyhow::Result<()> {
-        let testcases = [("babad", "bab"), ("cbbd", "bb")];
-
-        for (input, expect) in testcases {
+        for (input, expect) in TEST_CASES {
             let output = Self::longest_palindrome(input.into());
 
             if expect != output {
@@ -71,3 +71,64 @@ impl SolutionImpl {
         true
     }
 }
+
+pub struct SolutionImplDP;
+
+impl Solution for SolutionImplDP {
+    fn name(&self) -> String {
+        "Solution for Longest Palindromic Substring with Dynamic Programming".into()
+    }
+    fn problem_id(&self) -> usize {
+        5
+    }
+    fn location(&self) -> String {
+        crate::location!();
+    }
+    fn test(&self) -> anyhow::Result<()> {
+        for (input, expect) in TEST_CASES {
+            let output = Self::longest_palindrome(input.into());
+
+            if expect != output {
+                anyhow::bail!("test failed for input={input}, expect={expect}, output={output}");
+            }
+        }
+
+        Ok(())
+    }
+    fn benchmark(&self) -> anyhow::Result<usize> {
+        anyhow::bail!("TODO");
+    }
+}
+
+impl SolutionImplDP {
+    pub fn longest_palindrome(s: String) -> String {
+        let chars: Vec<char> = s.chars().collect();
+        let len = chars.len();
+        let mut result = "";
+        let mut dp = vec![vec![false; len]; len];
+
+        for (i, row) in dp.iter_mut().enumerate() {
+            row[i] = true;
+        }
+
+        for (i, row) in dp.iter_mut().enumerate().take(len - 1) {
+            row[i + 1] = chars[i] == chars[i + 1];
+        }
+
+        for diff in 0..len {
+            for i in 0..len - diff {
+                let j = i + diff;
+
+                if j - i > 1 {
+                    dp[i][j] = dp[i + 1][j - 1] && chars[i] == chars[j];
+                }
+
+                if dp[i][j] && j - i + 1 > result.len() {
+                    result = &s[i..j + 1];
+                }
+            }
+        }
+
+        result.into()
+    }
+}

runtime/src/registration.rs

@@ -18,6 +18,7 @@ pub fn register_all(handle: ContainerHandle) -> anyhow::Result<()> {
 
     handle.register_problem(|_| problems::longest_palindromic_substring::ProblemImpl)?;
     handle.register_solution(|_| solutions::longest_palindromic_substring::SolutionImpl)?;
+    handle.register_solution(|_| solutions::longest_palindromic_substring::SolutionImplDP)?;
 
     Ok(())
 }