Improved tasks 3408, 3419, 3433, 3434, 3435, 3472

src/main/kotlin/g3401_3500/s3408_design_task_manager/TaskManager.kt

@@ -6,17 +6,14 @@ package g3401_3500.s3408_design_task_manager
 import java.util.TreeSet
 
 class TaskManager(tasks: List<List<Int>>) {
-    private val tasks: TreeSet<IntArray?>
-    private val taskMap: MutableMap<Int?, IntArray>
+    private val tasks: TreeSet<IntArray> = TreeSet<IntArray>(
+        Comparator { a: IntArray, b: IntArray ->
+            if (b[2] == a[2]) b[1] - a[1] else b[2] - a[2]
+        },
+    )
+    private val taskMap: MutableMap<Int, IntArray> = HashMap<Int, IntArray>()
 
     init {
-        this.tasks =
-            TreeSet<IntArray?>(
-                Comparator { a: IntArray?, b: IntArray? ->
-                    if (b!![2] == a!![2]) b[1] - a[1] else b[2] - a[2]
-                },
-            )
-        this.taskMap = HashMap<Int?, IntArray>()
         for (task in tasks) {
             val t = intArrayOf(task[0], task[1], task[2])
             this.tasks.add(t)

src/main/kotlin/g3401_3500/s3419_minimize_the_maximum_edge_weight_of_graph/Solution.kt

@@ -10,27 +10,24 @@ import kotlin.math.max
 @Suppress("unused")
 class Solution {
     fun minMaxWeight(n: Int, edges: Array<IntArray>, threshold: Int): Int {
-        val reversedG: Array<MutableList<IntArray>?> = arrayOfNulls<MutableList<IntArray>?>(n)
-        for (i in 0..<n) {
-            reversedG[i] = ArrayList<IntArray>()
-        }
+        val reversedG: Array<MutableList<IntArray>> = Array<MutableList<IntArray>>(n) { ArrayList<IntArray>() }
         for (i in edges) {
             val a = i[0]
             val b = i[1]
             val w = i[2]
-            reversedG[b]!!.add(intArrayOf(a, w))
+            reversedG[b].add(intArrayOf(a, w))
         }
         val distance = IntArray(n)
         distance.fill(Int.Companion.MAX_VALUE)
         distance[0] = 0
-        if (reversedG[0]!!.isEmpty()) {
+        if (reversedG[0].isEmpty()) {
             return -1
         }
-        val que: Queue<Int?> = LinkedList<Int?>()
+        val que: Queue<Int> = LinkedList<Int>()
         que.add(0)
         while (que.isNotEmpty()) {
             val cur: Int = que.poll()!!
-            for (next in reversedG[cur]!!) {
+            for (next in reversedG[cur]) {
                 val node = next[0]
                 val w = next[1]
                 val nextdis = max(w, distance[cur])

src/main/kotlin/g3401_3500/s3433_count_mentions_per_user/Solution.kt

@@ -6,7 +6,7 @@ package g3401_3500.s3433_count_mentions_per_user
 class Solution {
     fun countMentions(numberOfUsers: Int, events: List<List<String>>): IntArray {
         val ans = IntArray(numberOfUsers)
-        val l: MutableList<Int?> = ArrayList<Int?>()
+        val l: MutableList<Int> = ArrayList<Int>()
         var c = 0
         for (i in events.indices) {
             val s = events[i][0]
@@ -31,7 +31,7 @@ class Solution {
                 val id = events[i][2].toInt()
                 val a = events[i][1].toInt() + 60
                 for (j in l.indices) {
-                    if (l[j]!! >= a - 60 && l[j]!! < a) {
+                    if (l[j] >= a - 60 && l[j] < a) {
                         ans[id]--
                     }
                 }

src/main/kotlin/g3401_3500/s3434_maximum_frequency_after_subarray_operation/Solution.kt

@@ -7,15 +7,15 @@ import kotlin.math.max
 
 class Solution {
     fun maxFrequency(nums: IntArray, k: Int): Int {
-        val count: MutableMap<Int?, Int?> = HashMap<Int?, Int?>()
+        val count: MutableMap<Int, Int> = HashMap<Int, Int>()
         for (a in nums) {
-            count.put(a, count.getOrDefault(a, 0)!! + 1)
+            count.put(a, count.getOrDefault(a, 0) + 1)
         }
         var res = 0
         for (b in count.keys) {
-            res = max(res, kadane(nums, k, b!!))
+            res = max(res, kadane(nums, k, b))
         }
-        return count.getOrDefault(k, 0)!! + res
+        return count.getOrDefault(k, 0) + res
     }
 
     private fun kadane(nums: IntArray, k: Int, b: Int): Int {

src/main/kotlin/g3401_3500/s3435_frequencies_of_shortest_supersequences/Solution.kt

@@ -11,7 +11,7 @@ class Solution {
     private val charToIdx = IntArray(26)
     private val used = BooleanArray(26)
 
-    fun supersequences(words: Array<String>): MutableList<MutableList<Int?>?> {
+    fun supersequences(words: Array<String>): List<List<Int>> {
         charToIdx.fill(-1)
         for (w in words) {
             used[w[0].code - 'a'.code] = true
@@ -37,7 +37,7 @@ class Solution {
         }
         // Try all supersets of forcedMask; keep those that kill all cycles
         var best = 9999
-        val goodSets: MutableList<Int?> = ArrayList<Int?>()
+        val goodSets: MutableList<Int> = ArrayList<Int>()
         for (s in 0..<(1 shl m)) {
             if ((s and forcedMask) != forcedMask) {
                 continue
@@ -52,16 +52,16 @@ class Solution {
             }
         }
         // Build distinct freq arrays from these sets
-        val seen: MutableSet<String?> = HashSet<String?>()
-        val ans: MutableList<MutableList<Int?>?> = ArrayList<MutableList<Int?>?>()
+        val seen: MutableSet<String> = HashSet<String>()
+        val ans: MutableList<MutableList<Int>> = ArrayList<MutableList<Int>>()
         for (s in goodSets) {
             val freq = IntArray(26)
             for (i in 0..<m) {
-                freq[idxToChar[i].code - 'a'.code] = if ((s!! and (1 shl i)) != 0) 2 else 1
+                freq[idxToChar[i].code - 'a'.code] = if ((s and (1 shl i)) != 0) 2 else 1
             }
             val key = freq.contentToString()
             if (seen.add(key)) {
-                val tmp: MutableList<Int?> = ArrayList<Int?>()
+                val tmp: MutableList<Int> = ArrayList<Int>()
                 for (f in freq) {
                     tmp.add(f)
                 }

src/main/kotlin/g3401_3500/s3472_longest_palindromic_subsequence_after_at_most_k_operations/Solution.kt

@@ -12,7 +12,7 @@ class Solution {
         val arr = Array<IntArray>(26) { IntArray(26) }
         for (i in 0..25) {
             for (j in 0..25) {
-                arr[i][j] = min(abs(i - j), (26 - abs(i - j)))
+                arr[i][j] = min(abs(i - j), 26 - abs(i - j))
             }
         }
         val dp = Array<Array<IntArray>>(n) { Array<IntArray>(n) { IntArray(k + 1) } }