Improved tasks 815, 819, 831, 843, 855, 857

Author: javadev

src/main/kotlin/g0801_0900/s0815_bus_routes/Solution.kt

@@ -5,9 +5,6 @@ package g0801_0900.s0815_bus_routes
 
 import java.util.LinkedList
 import java.util.Queue
-import kotlin.collections.ArrayList
-import kotlin.collections.HashSet
-import kotlin.collections.MutableSet
 
 class Solution {
     fun numBusesToDestination(routes: Array<IntArray>, source: Int, target: Int): Int {

src/main/kotlin/g0801_0900/s0819_most_common_word/Solution.kt

@@ -2,16 +2,14 @@ package g0801_0900.s0819_most_common_word
 
 // #Easy #String #Hash_Table #Counting #2023_03_24_Time_211_ms_(83.33%)_Space_36.9_MB_(88.89%)
 
-import java.util.Locale
-
 @Suppress("NAME_SHADOWING")
 class Solution {
     fun mostCommonWord(paragraph: String, banned: Array<String>): String {
         var paragraph = paragraph
-        paragraph = paragraph.replace("\\p{Punct}".toRegex(), " ").lowercase(Locale.getDefault())
+        paragraph = paragraph.replace("\\p{Punct}".toRegex(), " ").lowercase()
         val a = paragraph.split(" ".toRegex()).dropLastWhile { it.isEmpty() }.toTypedArray()
         for (i in banned.indices) {
-            banned[i] = banned[i].lowercase(Locale.getDefault())
+            banned[i] = banned[i].lowercase()
         }
         val map: MutableMap<String, Int> = HashMap()
         for (s in a) {

src/main/kotlin/g0801_0900/s0831_masking_personal_information/Solution.kt

@@ -2,15 +2,13 @@ package g0801_0900.s0831_masking_personal_information
 
 // #Medium #String #2023_03_25_Time_149_ms_(100.00%)_Space_35.3_MB_(100.00%)
 
-import java.util.Locale
-
 class Solution {
     fun maskPII(s: String): String {
         val masked = StringBuilder()
         return if (Character.isAlphabetic(s[0].code)) {
             val locationOfAtSymbol = s.indexOf("@") - 1
             masked.append(s[0]).append("*****").append(s.substring(locationOfAtSymbol))
-            masked.toString().lowercase(Locale.getDefault())
+            masked.toString().lowercase()
         } else {
             val allDigits = StringBuilder()
             var pointer = -1

src/main/kotlin/g0801_0900/s0843_guess_the_word/Solution.kt

@@ -3,8 +3,6 @@ package g0801_0900.s0843_guess_the_word
 // #Hard #Array #String #Math #Game_Theory #Interactive
 // #2023_03_29_Time_75_ms_(100.00%)_Space_31.5_MB_(100.00%)
 
-import java.util.Collections
-
 /*
  * // This is the Master's API interface.
  * // You should not implement it, or speculate about its implementation
@@ -20,8 +18,8 @@ class Solution {
     private var next = 0
 
     fun findSecretWord(wordlist: Array<String>, master: Master) {
-        val list = listOf(*wordlist)
-        Collections.shuffle(list)
+        val list = wordlist.copyOf()
+        list.shuffle()
         val test = BooleanArray(wordlist.size)
         while (true) {
             val num = master.guess(list[next])
@@ -32,7 +30,7 @@ class Solution {
         }
     }
 
-    private fun updateList(list: List<String?>, test: BooleanArray, num: Int) {
+    private fun updateList(list: Array<String>, test: BooleanArray, num: Int) {
         val index = next
         for (i in index + 1 until test.size) {
             if (test[i]) {
@@ -47,10 +45,10 @@ class Solution {
         }
     }
 
-    private fun getSame(word1: String?, word2: String?): Int {
+    private fun getSame(word1: String, word2: String): Int {
         var ret = 0
         for (i in 0..5) {
-            if (word1!![i] == word2!![i]) {
+            if (word1[i] == word2[i]) {
                 ret++
             }
         }

src/main/kotlin/g0801_0900/s0855_exam_room/ExamRoom.kt

@@ -2,8 +2,6 @@ package g0801_0900.s0855_exam_room
 
 // #Medium #Design #Ordered_Set #2023_03_31_Time_644_ms_(83.33%)_Space_40.4_MB_(100.00%)
 
-import java.util.Objects
-
 class ExamRoom() {
     private class Node(var `val`: Int, map: MutableMap<Int?, Node>) {
         var pre: Node? = null
@@ -67,7 +65,7 @@ class ExamRoom() {
         }
         return if (right > max) {
             Node(n - 1, map).insert(tail.pre)
-        } else Node(maxAt, map).insert(Objects.requireNonNull(maxAtLeft))
+        } else Node(maxAt, map).insert(maxAtLeft)
     }
 
     fun leave(p: Int) {

src/main/kotlin/g0801_0900/s0857_minimum_cost_to_hire_k_workers/Solution.kt

@@ -13,10 +13,8 @@ class Solution {
             workers[i] = Worker(wage[i], quality[i])
         }
         workers.sortBy { it!!.ratio() }
-        val maxHeap = PriorityQueue { a: Int?, b: Int? ->
-            Integer.compare(
-                b!!, a!!
-            )
+        val maxHeap = PriorityQueue { a: Int, b: Int ->
+            b.compareTo(a)
         }
         var sumQuality = 0
         var result = Double.MAX_VALUE