add new problem 30.05

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

@@ -1,10 +1,10 @@
 package com.github.contest
 
 
+import com.github.contest.design.wrapper
 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.numberOfAlternatingGroups
 import com.github.contest.strings.fullJustify
 import com.github.contest.strings.subStrHash
 import java.util.TreeMap
@@ -16,7 +16,7 @@ import java.util.TreeMap
 
 fun main() {
 
-    numberOfAlternatingGroups(intArrayOf(0, 1, 0)).also { println(it) }
+    wrapper()
 }
 
 

contest/src/main/java/com/github/contest/design/DesignLeetcode.kt

@@ -180,4 +180,69 @@ class RandomizedSet() {
 
     fun getRandom(): Int = store.keys.random()
 
+}
+
+/**
+ * 284. Peeking Iterator
+ */
+
+class PeekingIterator(iterator: Iterator<Int>) : Iterator<Int> {
+
+    private val store = mutableListOf<Int>()
+
+    init {
+        while (iterator.hasNext()) store.add(iterator.next())
+    }
+
+    fun peek(): Int {
+        return store.first()
+    }
+
+    override fun next(): Int {
+        return store.removeFirst()
+    }
+
+    override fun hasNext(): Boolean {
+        return store.isNotEmpty()
+    }
+}
+
+/**
+ * 1286. Iterator for Combination
+ */
+
+class CombinationIterator(characters: String, combinationLength: Int) {
+
+    private val store = mutableListOf<String>()
+
+    init {
+        combine(0, characters, StringBuilder(), store, combinationLength)
+    }
+
+    fun next(): String = store.removeFirst()
+
+    fun hasNext(): Boolean = store.isNotEmpty()
+
+    private fun combine(
+        index: Int,
+        str: String,
+        subset: StringBuilder,
+        store: MutableList<String>,
+        limit: Int
+    ) {
+
+        if (subset.length == limit) {
+            store.add(subset.toString())
+            return
+        }
+
+        if (index == str.length) return
+
+        subset.append(str[index])
+        combine(index + 1, str, subset, store, limit)
+
+        subset.deleteAt(subset.length - 1)
+        combine(index + 1, str, subset, store, limit)
+    }
+
 }

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

@@ -166,4 +166,19 @@ fun findLHSProdVariant(nums: IntArray): Int =
         }
     }
 
+fun findLHSProdVariantII(nums: IntArray): Int {
+    val freq = nums.groupBy { it }.mapValues { it.value.size }
+
+    return freq.asSequence()
+        .flatMap { (key, _) ->
+            sequenceOf(
+                key to (key + 1),  // Check next number
+                key to (key - 1)   // Also check previous number (optional)
+            )
+        }
+        .filter { (_, adjacent) -> freq.containsKey(adjacent) }
+        .maxOfOrNull { (key, adjacent) -> freq[key]!! + freq[adjacent]!! }
+        ?: 0
+}
+