feat: add solutions to lc problem: No.0409

No.0409.Longest Palindrome

Author: YangFong

solution/0400-0499/0409.Longest Palindrome/README.md

@@ -102,6 +102,25 @@ function longestPalindrome(s: string): number {
 }
 ```
 
+```ts
+function longestPalindrome(s: string): number {
+    const map = new Map();
+    for (const c of s) {
+        map.set(c, (map.get(c) ?? 0) + 1);
+    }
+    let hasOdd = false;
+    let res = 0;
+    for (const v of map.values()) {
+        res += v;
+        if (v & 1) {
+            hasOdd = true;
+            res--;
+        }
+    }
+    return res + (hasOdd ? 1 : 0);
+}
+```
+
 ### **C++**
 
 ```cpp
@@ -138,6 +157,31 @@ func longestPalindrome(s string) int {
 }
 ```
 
+### **Rust**
+
+```rust
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn longest_palindrome(s: String) -> i32 {
+        let mut map: HashMap<char, i32> = HashMap::new();
+        for c in s.chars() {
+            map.insert(c, map.get(&c).unwrap_or(&0) + 1);
+        }
+        let mut has_odd = false;
+        let mut res = 0;
+        for v in map.values() {
+            res += v;
+            if v % 2 == 1 {
+                has_odd = true;
+                res -= 1;
+            }
+        }
+        res + if has_odd { 1 } else { 0 }
+    }
+}
+```
+
 ### **...**
 
 ```

solution/0400-0499/0409.Longest Palindrome/README_EN.md

@@ -92,6 +92,25 @@ function longestPalindrome(s: string): number {
 }
 ```
 
+```ts
+function longestPalindrome(s: string): number {
+    const map = new Map();
+    for (const c of s) {
+        map.set(c, (map.get(c) ?? 0) + 1);
+    }
+    let hasOdd = false;
+    let res = 0;
+    for (const v of map.values()) {
+        res += v;
+        if (v & 1) {
+            hasOdd = true;
+            res--;
+        }
+    }
+    return res + (hasOdd ? 1 : 0);
+}
+```
+
 ### **C++**
 
 ```cpp
@@ -128,6 +147,31 @@ func longestPalindrome(s string) int {
 }
 ```
 
+### **Rust**
+
+```rust
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn longest_palindrome(s: String) -> i32 {
+        let mut map: HashMap<char, i32> = HashMap::new();
+        for c in s.chars() {
+            map.insert(c, map.get(&c).unwrap_or(&0) + 1);
+        }
+        let mut has_odd = false;
+        let mut res = 0;
+        for v in map.values() {
+            res += v;
+            if v % 2 == 1 {
+                has_odd = true;
+                res -= 1;
+            }
+        }
+        res + if has_odd { 1 } else { 0 }
+    }
+}
+```
+
 ### **...**
 
 ```

solution/0400-0499/0409.Longest Palindrome/Solution.rs

@@ -0,0 +1,20 @@
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn longest_palindrome(s: String) -> i32 {
+        let mut map: HashMap<char, i32> = HashMap::new();
+        for c in s.chars() {
+            map.insert(c, map.get(&c).unwrap_or(&0) + 1);
+        }
+        let mut has_odd = false;
+        let mut res = 0;
+        for v in map.values() {
+            res += v;
+            if v % 2 == 1 {
+                has_odd = true;
+                res -= 1;
+            }
+        }
+        res + if has_odd { 1 } else { 0 }
+    }
+}