add new problems 25.05

contest/src/main/java/com/github/contest/Execute.kt

@@ -1,10 +1,10 @@
 package com.github.contest
 
 
+import com.github.contest.hashTable.longestPalindromeAlternativeSolution
 import com.github.contest.math.numberOfPowerfulInt
 import com.github.contest.slidingWindow.customStructure.rabinKarpMultiPattern
 import com.github.contest.slidingWindow.customStructure.slidingWindowClassic
-import com.github.contest.slidingWindow.maximumRobots
 import com.github.contest.strings.fullJustify
 import com.github.contest.strings.subStrHash
 import java.util.TreeMap
@@ -15,7 +15,11 @@ import java.util.TreeMap
  */
 
 fun main() {
-    maximumRobots(intArrayOf(3, 6, 1, 3, 4), intArrayOf(2, 1, 3, 4, 5), 25).also { println(it) }
+
+    val arr = arrayOf("em", "pe", "mp", "ee", "pp", "me", "ep", "em", "em", "me")
+    longestPalindromeAlternativeSolution(
+        arr
+    ).also { println(it) }
 }
 
 

contest/src/main/java/com/github/contest/hashTable/HashTableAlternativeSolution.kt

@@ -114,4 +114,32 @@ fun findEvenNumbersAlternativeSolution(digits: IntArray): IntArray {
     }
 
     return result.sorted().toIntArray()
-}
+}
+
+/**
+ * 2131. Longest Palindrome by Concatenating Two Letter Words
+ */
+
+fun longestPalindromeAlternativeSolution(words: Array<String>): Int {
+    val freq = words.groupingBy { it }.eachCount().toMutableMap()
+    var len = 0
+    var centralPair = 0
+
+    for ((word, count) in freq) {
+        if (word[0] == word[1]) {
+            if (count % 2 == 0) {
+                len += (count * 2)
+            } else {
+                len += (count - 1) * 2
+                centralPair = 2
+            }
+        } else {
+            val mirror = "${word[1]}${word[0]}"
+            val minPairs = minOf(count, freq.getOrDefault(mirror, 0))
+            len += (minPairs * 4)
+            freq[word] = 0
+        }
+    }
+
+    return len + centralPair
+}

contest/src/main/java/com/github/contest/hashTable/HashTableLeetcode.kt

@@ -556,3 +556,42 @@ fun findEvenNumbers(digits: IntArray): IntArray {
 
     return result.sorted().toIntArray()
 }
+
+/**
+ * 2131. Longest Palindrome by Concatenating Two Letter Words
+ */
+
+fun longestPalindrome(words: Array<String>): Int {
+    var len = 0
+    val freq = mutableMapOf<String, Int>()
+
+    for (origin in words) {
+        val reverse = "${origin[1]}${origin[0]}"
+
+        when {
+            origin == reverse -> {
+                if (freq.contains(origin)) {
+                    len += 4
+                    freq.remove(origin)
+                } else freq[origin] = freq.getOrDefault(origin, 0) + 1
+            }
+
+            freq.contains(reverse) -> {
+                freq[reverse] = freq.getOrDefault(reverse, 0) - 1
+                len += 4
+                if (freq[reverse] == 0) freq.remove(reverse)
+            }
+
+            else -> freq[origin] = freq.getOrDefault(origin, 0) + 1
+        }
+    }
+
+    for ((key, value) in freq) {
+        if ((key[0] == key[1]) && value == 1) {
+            len += 2
+            break
+        }
+    }
+
+    return len
+}