Added tasks 2857-2900

README.md

@@ -1154,7 +1154,7 @@
 | 0977 |[Squares of a Sorted Array](src/main/kotlin/g0901_1000/s0977_squares_of_a_sorted_array)| Easy | Array, Sorting, Two_Pointers | 271 | 77.17
 | 0026 |[Remove Duplicates from Sorted Array](src/main/kotlin/g0001_0100/s0026_remove_duplicates_from_sorted_array)| Easy | Top_Interview_Questions, Array, Two_Pointers | 249 | 67.38
 | 0042 |[Trapping Rain Water](src/main/kotlin/g0001_0100/s0042_trapping_rain_water)| Hard | Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Two_Pointers, Stack, Monotonic_Stack, Big_O_Time_O(n)_Space_O(1) | 189 | 99.37
-| 0015 |[3Sum](src/main/kotlin/g0001_0100/s0015_3sum)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n^2)_Space_O(1) | 493 | 93.45
+| 0015 |[3Sum](src/main/kotlin/g0001_0100/s0015_3sum)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n\*log(n))_Space_O(n^2) | 493 | 93.45
 
 #### Udemy Famous Algorithm
 
@@ -1406,7 +1406,7 @@
 |-|-|-|-|-|-
 | 0136 |[Single Number](src/main/kotlin/g0101_0200/s0136_single_number)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Big_O_Time_O(N)_Space_O(1) | 344 | 83.63
 | 0169 |[Majority Element](src/main/kotlin/g0101_0200/s0169_majority_element)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Sorting, Counting, Divide_and_Conquer, Big_O_Time_O(n)_Space_O(1) | 460 | 51.25
-| 0015 |[3Sum](src/main/kotlin/g0001_0100/s0015_3sum)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n^2)_Space_O(1) | 493 | 93.45
+| 0015 |[3Sum](src/main/kotlin/g0001_0100/s0015_3sum)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n\*log(n))_Space_O(n^2) | 493 | 93.45
 
 #### Day 2 Array
 
@@ -1680,7 +1680,7 @@
 | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
 |-|-|-|-|-|-
 | 0082 |[Remove Duplicates from Sorted List II](src/main/kotlin/g0001_0100/s0082_remove_duplicates_from_sorted_list_ii)| Medium | Two_Pointers, Linked_List | 166 | 89.47
-| 0015 |[3Sum](src/main/kotlin/g0001_0100/s0015_3sum)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n^2)_Space_O(1) | 493 | 93.45
+| 0015 |[3Sum](src/main/kotlin/g0001_0100/s0015_3sum)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n\*log(n))_Space_O(n^2) | 493 | 93.45
 
 #### Day 4 Two Pointers
 
@@ -1816,6 +1816,45 @@
 
 | #    |      Title     | Difficulty  | Tag         | Time, ms | Time, %
 |------|----------------|-------------|-------------|----------|--------
+| 2900 |[Longest Unequal Adjacent Groups Subsequence I](src/main/kotlin/g2801_2900/s2900_longest_unequal_adjacent_groups_subsequence_i)| Medium | Array, String, Dynamic_Programming, Greedy | 294 | 100.00
+| 2899 |[Last Visited Integers](src/main/kotlin/g2801_2900/s2899_last_visited_integers)| Easy | Array, String, Simulation | 209 | 72.73
+| 2897 |[Apply Operations on Array to Maximize Sum of Squares](src/main/kotlin/g2801_2900/s2897_apply_operations_on_array_to_maximize_sum_of_squares)| Hard | Array, Hash_Table, Greedy, Bit_Manipulation | 572 | 100.00
+| 2896 |[Apply Operations to Make Two Strings Equal](src/main/kotlin/g2801_2900/s2896_apply_operations_to_make_two_strings_equal)| Medium | String, Dynamic_Programming | 181 | 66.67
+| 2895 |[Minimum Processing Time](src/main/kotlin/g2801_2900/s2895_minimum_processing_time)| Medium | Array, Sorting, Greedy | 662 | 80.00
+| 2894 |[Divisible and Non-divisible Sums Difference](src/main/kotlin/g2801_2900/s2894_divisible_and_non_divisible_sums_difference)| Easy | Math | 135 | 76.92
+| 2891 |[Method Chaining](src/main/kotlin/g2801_2900/s2891_method_chaining)| Easy || 412 | 99.23
+| 2890 |[Reshape Data: Melt](src/main/kotlin/g2801_2900/s2890_reshape_data_melt)| Easy || 446 | 97.89
+| 2889 |[Reshape Data: Pivot](src/main/kotlin/g2801_2900/s2889_reshape_data_pivot)| Easy || 416 | 99.87
+| 2888 |[Reshape Data: Concatenate](src/main/kotlin/g2801_2900/s2888_reshape_data_concatenate)| Easy || 441 | 96.26
+| 2887 |[Fill Missing Data](src/main/kotlin/g2801_2900/s2887_fill_missing_data)| Easy || 404 | 97.11
+| 2886 |[Change Data Type](src/main/kotlin/g2801_2900/s2886_change_data_type)| Easy || 421 | 94.57
+| 2885 |[Rename Columns](src/main/kotlin/g2801_2900/s2885_rename_columns)| Easy || 467 | 68.13
+| 2884 |[Modify Columns](src/main/kotlin/g2801_2900/s2884_modify_columns)| Easy || 401 | 96.35
+| 2883 |[Drop Missing Data](src/main/kotlin/g2801_2900/s2883_drop_missing_data)| Easy || 429 | 94.97
+| 2882 |[Drop Duplicate Rows](src/main/kotlin/g2801_2900/s2882_drop_duplicate_rows)| Easy || 405 | 97.36
+| 2881 |[Create a New Column](src/main/kotlin/g2801_2900/s2881_create_a_new_column)| Easy || 437 | 81.98
+| 2880 |[Select Data](src/main/kotlin/g2801_2900/s2880_select_data)| Easy || 428 | 94.99
+| 2879 |[Display the First Three Rows](src/main/kotlin/g2801_2900/s2879_display_the_first_three_rows)| Easy || 406 | 96.44
+| 2878 |[Get the Size of a DataFrame](src/main/kotlin/g2801_2900/s2878_get_the_size_of_a_dataframe)| Easy || 413 | 94.68
+| 2877 |[Create a DataFrame from List](src/main/kotlin/g2801_2900/s2877_create_a_dataframe_from_list)| Easy || 406 | 82.57
+| 2876 |[Count Visited Nodes in a Directed Graph](src/main/kotlin/g2801_2900/s2876_count_visited_nodes_in_a_directed_graph)| Hard | Dynamic_Programming, Graph, Memoization | 922 | 100.00
+| 2875 |[Minimum Size Subarray in Infinite Array](src/main/kotlin/g2801_2900/s2875_minimum_size_subarray_in_infinite_array)| Medium | Array, Hash_Table, Prefix_Sum, Sliding_Window | 372 | 100.00
+| 2874 |[Maximum Value of an Ordered Triplet II](src/main/kotlin/g2801_2900/s2874_maximum_value_of_an_ordered_triplet_ii)| Medium | Array | 508 | 100.00
+| 2873 |[Maximum Value of an Ordered Triplet I](src/main/kotlin/g2801_2900/s2873_maximum_value_of_an_ordered_triplet_i)| Easy | Array | 157 | 94.12
+| 2872 |[Maximum Number of K-Divisible Components](src/main/kotlin/g2801_2900/s2872_maximum_number_of_k_divisible_components)| Hard | Dynamic_Programming, Depth_First_Search, Tree | 780 | 100.00
+| 2871 |[Split Array Into Maximum Number of Subarrays](src/main/kotlin/g2801_2900/s2871_split_array_into_maximum_number_of_subarrays)| Medium | Array, Greedy, Bit_Manipulation | 490 | 100.00
+| 2870 |[Minimum Number of Operations to Make Array Empty](src/main/kotlin/g2801_2900/s2870_minimum_number_of_operations_to_make_array_empty)| Medium | Array, Hash_Table, Greedy, Counting | 503 | 80.00
+| 2869 |[Minimum Operations to Collect Elements](src/main/kotlin/g2801_2900/s2869_minimum_operations_to_collect_elements)| Easy | Array, Hash_Table | 156 | 100.00
+| 2867 |[Count Valid Paths in a Tree](src/main/kotlin/g2801_2900/s2867_count_valid_paths_in_a_tree)| Hard | Dynamic_Programming, Math, Depth_First_Search, Tree, Number_Theory | 793 | 100.00
+| 2866 |[Beautiful Towers II](src/main/kotlin/g2801_2900/s2866_beautiful_towers_ii)| Medium | Array, Stack, Monotonic_Stack | 676 | 85.71
+| 2865 |[Beautiful Towers I](src/main/kotlin/g2801_2900/s2865_beautiful_towers_i)| Medium | Array, Stack, Monotonic_Stack | 232 | 75.00
+| 2864 |[Maximum Odd Binary Number](src/main/kotlin/g2801_2900/s2864_maximum_odd_binary_number)| Easy | String, Math, Greedy | 176 | 90.91
+| 2862 |[Maximum Element-Sum of a Complete Subset of Indices](src/main/kotlin/g2801_2900/s2862_maximum_element_sum_of_a_complete_subset_of_indices)| Hard | Array, Math, Number_Theory | 259 | 100.00
+| 2861 |[Maximum Number of Alloys](src/main/kotlin/g2801_2900/s2861_maximum_number_of_alloys)| Medium | Array, Binary_Search | 289 | 100.00
+| 2860 |[Happy Students](src/main/kotlin/g2801_2900/s2860_happy_students)| Medium | Array, Sorting, Enumeration | 512 | 100.00
+| 2859 |[Sum of Values at Indices With K Set Bits](src/main/kotlin/g2801_2900/s2859_sum_of_values_at_indices_with_k_set_bits)| Easy | Array, Bit_Manipulation | 177 | 100.00
+| 2858 |[Minimum Edge Reversals So Every Node Is Reachable](src/main/kotlin/g2801_2900/s2858_minimum_edge_reversals_so_every_node_is_reachable)| Hard | Dynamic_Programming, Depth_First_Search, Breadth_First_Search, Graph | 1161 | 100.00
+| 2857 |[Count Pairs of Points With Distance k](src/main/kotlin/g2801_2900/s2857_count_pairs_of_points_with_distance_k)| Medium | Array, Hash_Table, Bit_Manipulation | 1212 | 100.00
 | 2856 |[Minimum Array Length After Pair Removals](src/main/kotlin/g2801_2900/s2856_minimum_array_length_after_pair_removals)| Medium | Array, Hash_Table, Greedy, Binary_Search, Two_Pointers, Counting | 647 | 100.00
 | 2855 |[Minimum Right Shifts to Sort the Array](src/main/kotlin/g2801_2900/s2855_minimum_right_shifts_to_sort_the_array)| Easy | Array | 169 | 75.00
 | 2851 |[String Transformation](src/main/kotlin/g2801_2900/s2851_string_transformation)| Hard | String, Dynamic_Programming, Math, String_Matching | 377 | 100.00
@@ -4085,7 +4124,7 @@
 | 0018 |[4Sum](src/main/kotlin/g0001_0100/s0018_4sum)| Medium | Array, Sorting, Two_Pointers | 229 | 98.59
 | 0017 |[Letter Combinations of a Phone Number](src/main/kotlin/g0001_0100/s0017_letter_combinations_of_a_phone_number)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Backtracking, Algorithm_II_Day_11_Recursion_Backtracking, Udemy_Backtracking/Recursion, Big_O_Time_O(4^n)_Space_O(n) | 155 | 95.24
 | 0016 |[3Sum Closest](src/main/kotlin/g0001_0100/s0016_3sum_closest)| Medium | Array, Sorting, Two_Pointers, Level_2_Day_14_Sliding_Window/Two_Pointer | 163 | 100.00
-| 0015 |[3Sum](src/main/kotlin/g0001_0100/s0015_3sum)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Data_Structure_II_Day_1_Array, Algorithm_II_Day_3_Two_Pointers, Udemy_Two_Pointers, Big_O_Time_O(n^2)_Space_O(1) | 493 | 93.45
+| 0015 |[3Sum](src/main/kotlin/g0001_0100/s0015_3sum)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Data_Structure_II_Day_1_Array, Algorithm_II_Day_3_Two_Pointers, Udemy_Two_Pointers, Big_O_Time_O(n\*log(n))_Space_O(n^2) | 493 | 93.45
 | 0014 |[Longest Common Prefix](src/main/kotlin/g0001_0100/s0014_longest_common_prefix)| Easy | Top_Interview_Questions, String, Level_2_Day_2_String, Udemy_Strings | 154 | 89.70
 | 0013 |[Roman to Integer](src/main/kotlin/g0001_0100/s0013_roman_to_integer)| Easy | Top_Interview_Questions, String, Hash_Table, Math | 211 | 83.47
 | 0012 |[Integer to Roman](src/main/kotlin/g0001_0100/s0012_integer_to_roman)| Medium | String, Hash_Table, Math | 180 | 98.25

src/main/kotlin/g2801_2900/s2815_max_pair_sum_in_an_array/readme.md

@@ -43,6 +43,7 @@ import java.util.PriorityQueue
 import kotlin.collections.HashMap
 import kotlin.math.max
 
+@Suppress("NAME_SHADOWING")
 class Solution {
     fun maxSum(nums: IntArray): Int {
         // what we'll return

src/main/kotlin/g2801_2900/s2827_number_of_beautiful_integers_in_the_range/readme.md

@@ -54,6 +54,7 @@ Return _the number of beautiful integers in the range_ `[low, high]`.
 ```kotlin
 import kotlin.math.max
 
+@Suppress("kotlin:S107")
 class Solution {
     private lateinit var dp: Array<Array<Array<Array<IntArray>>>>
     private var maxLength = 0

src/main/kotlin/g2801_2900/s2829_determine_the_minimum_sum_of_a_k_avoiding_array/readme.md

@@ -34,6 +34,7 @@ Return _the **minimum** possible sum of a k-avoiding array of length_ `n`.
 ## Solution
 
 ```kotlin
+@Suppress("NAME_SHADOWING")
 class Solution {
     fun minimumSum(n: Int, k: Int): Int {
         var k = k

src/main/kotlin/g2801_2900/s2835_minimum_operations_to_form_subsequence_with_target_sum/readme.md

@@ -77,7 +77,7 @@ class Solution {
         if (sum < target) {
             return -1
         }
-        while (!pq.isEmpty()) {
+        while (pq.isNotEmpty()) {
             val `val` = pq.poll()
             sum -= `val`.toLong()
             if (`val` <= target) {

src/main/kotlin/g2801_2900/s2842_count_k_subsequences_of_a_string_with_maximum_beauty/readme.md

@@ -73,6 +73,7 @@ There are 2 k-subsequences that have the maximum beauty, 5. Hence, the answer is
 ## Solution
 
 ```kotlin
+@Suppress("NAME_SHADOWING")
 class Solution {
     fun countKSubsequencesWithMaxBeauty(s: String, k: Int): Int {
         var k = k

src/main/kotlin/g2801_2900/s2846_minimum_edge_weight_equilibrium_queries_in_a_tree/readme.md

@@ -64,6 +64,7 @@ In the fourth query, we change the weights of edges [0,7], [0,3] and [1,3] to 6.
 import kotlin.math.ln
 import kotlin.math.max
 
+@Suppress("kotlin:S107")
 class Solution {
     private class Node(var v: Int, var w: Int)
 

src/main/kotlin/g2801_2900/s2855_minimum_right_shifts_to_sort_the_array/readme.md

@@ -48,6 +48,7 @@ Now nums is sorted; therefore the answer is 2.
 ## Solution
 
 ```kotlin
+@Suppress("kotlin:S6510")
 class Solution {
     fun minimumRightShifts(nums: List<Int>): Int {
         var i = 1

src/main/kotlin/g2801_2900/s2857_count_pairs_of_points_with_distance_k/readme.md

@@ -0,0 +1,67 @@
+[![](https://img.shields.io/github/stars/javadev/LeetCode-in-Kotlin?label=Stars&style=flat-square)](https://github.com/javadev/LeetCode-in-Kotlin)
+[![](https://img.shields.io/github/forks/javadev/LeetCode-in-Kotlin?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/javadev/LeetCode-in-Kotlin/fork)
+
+## 2857\. Count Pairs of Points With Distance k
+
+Medium
+
+You are given a **2D** integer array `coordinates` and an integer `k`, where <code>coordinates[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> are the coordinates of the <code>i<sup>th</sup></code> point in a 2D plane.
+
+We define the **distance** between two points <code>(x<sub>1</sub>, y<sub>1</sub>)</code> and <code>(x<sub>2</sub>, y<sub>2</sub>)</code> as `(x1 XOR x2) + (y1 XOR y2)` where `XOR` is the bitwise `XOR` operation.
+
+Return _the number of pairs_ `(i, j)` _such that_ `i < j` _and the distance between points_ `i` _and_ `j` _is equal to_ `k`.
+
+**Example 1:**
+
+**Input:** coordinates = \[\[1,2],[4,2],[1,3],[5,2]], k = 5
+
+**Output:** 2
+
+**Explanation:** We can choose the following pairs: 
+- (0,1): Because we have (1 XOR 4) + (2 XOR 2) = 5. 
+- (2,3): Because we have (1 XOR 5) + (3 XOR 2) = 5.
+
+**Example 2:**
+
+**Input:** coordinates = \[\[1,3],[1,3],[1,3],[1,3],[1,3]], k = 0
+
+**Output:** 10
+
+**Explanation:** Any two chosen pairs will have a distance of 0. There are 10 ways to choose two pairs.
+
+**Constraints:**
+
+*   `2 <= coordinates.length <= 50000`
+*   <code>0 <= x<sub>i</sub>, y<sub>i</sub> <= 10<sup>6</sup></code>
+*   `0 <= k <= 100`
+
+## Solution
+
+```kotlin
+class Solution {
+    fun countPairs(coordinates: List<List<Int>>, k: Int): Int {
+        var ans = 0
+        val map: MutableMap<Long, Int> = HashMap()
+        for (p in coordinates) {
+            val p0 = p[0]
+            val p1 = p[1]
+            for (i in 0..k) {
+                val x1 = i xor p0
+                val y1 = (k - i) xor p1
+                val key2 = hash(x1, y1)
+                if (map.containsKey(key2)) {
+                    ans += map[key2]!!
+                }
+            }
+            val key = hash(p0, p1)
+            map[key] = map.getOrDefault(key, 0) + 1
+        }
+        return ans
+    }
+
+    private fun hash(x1: Int, y1: Int): Long {
+        val r = 1e8.toLong()
+        return x1 * r + y1
+    }
+}
+```

src/main/kotlin/g2801_2900/s2858_minimum_edge_reversals_so_every_node_is_reachable/readme.md

@@ -0,0 +1,130 @@
+[![](https://img.shields.io/github/stars/javadev/LeetCode-in-Kotlin?label=Stars&style=flat-square)](https://github.com/javadev/LeetCode-in-Kotlin)
+[![](https://img.shields.io/github/forks/javadev/LeetCode-in-Kotlin?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/javadev/LeetCode-in-Kotlin/fork)
+
+## 2858\. Minimum Edge Reversals So Every Node Is Reachable
+
+Hard
+
+There is a **simple directed graph** with `n` nodes labeled from `0` to `n - 1`. The graph would form a **tree** if its edges were bi-directional.
+
+You are given an integer `n` and a **2D** integer array `edges`, where <code>edges[i] = [u<sub>i</sub>, v<sub>i</sub>]</code> represents a **directed edge** going from node <code>u<sub>i</sub></code> to node <code>v<sub>i</sub></code>.
+
+An **edge reversal** changes the direction of an edge, i.e., a directed edge going from node <code>u<sub>i</sub></code> to node <code>v<sub>i</sub></code> becomes a directed edge going from node <code>v<sub>i</sub></code> to node <code>u<sub>i</sub></code>.
+
+For every node `i` in the range `[0, n - 1]`, your task is to **independently** calculate the **minimum** number of **edge reversals** required so it is possible to reach any other node starting from node `i` through a **sequence** of **directed edges**.
+
+Return _an integer array_ `answer`_, where_ `answer[i]` _is the_ _**minimum** number of **edge reversals** required so it is possible to reach any other node starting from node_ `i` _through a **sequence** of **directed edges**._
+
+**Example 1:**
+
+![](https://assets.leetcode.com/uploads/2023/08/26/image-20230826221104-3.png)
+
+**Input:** n = 4, edges = \[\[2,0],[2,1],[1,3]]
+
+**Output:** [1,1,0,2]
+
+**Explanation:** The image above shows the graph formed by the edges. 
+
+For node 0: after reversing the edge [2,0], it is possible to reach any other node starting from node 0. 
+
+So, answer[0] = 1. 
+
+For node 1: after reversing the edge [2,1], it is possible to reach any other node starting from node 1. 
+
+So, answer[1] = 1. 
+
+For node 2: it is already possible to reach any other node starting from node 2. 
+
+So, answer[2] = 0. 
+
+For node 3: after reversing the edges [1,3] and [2,1], it is possible to reach any other node starting from node 3. 
+
+So, answer[3] = 2.
+
+**Example 2:**
+
+![](https://assets.leetcode.com/uploads/2023/08/26/image-20230826225541-2.png)
+
+**Input:** n = 3, edges = \[\[1,2],[2,0]]
+
+**Output:** [2,0,1]
+
+**Explanation:** The image above shows the graph formed by the edges. 
+
+For node 0: after reversing the edges [2,0] and [1,2], it is possible to reach any other node starting from node 0. 
+
+So, answer[0] = 2. 
+
+For node 1: it is already possible to reach any other node starting from node 1. 
+
+So, answer[1] = 0. 
+
+For node 2: after reversing the edge [1, 2], it is possible to reach any other node starting from node 2. 
+
+So, answer[2] = 1.
+
+**Constraints:**
+
+*   <code>2 <= n <= 10<sup>5</sup></code>
+*   `edges.length == n - 1`
+*   `edges[i].length == 2`
+*   <code>0 <= u<sub>i</sub> == edges[i][0] < n</code>
+*   <code>0 <= v<sub>i</sub> == edges[i][1] < n</code>
+*   <code>u<sub>i</sub> != v<sub>i</sub></code>
+*   The input is generated such that if the edges were bi-directional, the graph would be a tree.
+
+## Solution
+
+```kotlin
+import java.util.LinkedList
+import java.util.Queue
+
+class Solution {
+    fun minEdgeReversals(n: Int, edges: Array<IntArray>): IntArray {
+        val nexts: Array<MutableList<IntArray>> = Array(n) { ArrayList() }
+        for (edge in edges) {
+            val u = edge[0]
+            val v = edge[1]
+            nexts[u].add(intArrayOf(1, v))
+            nexts[v].add(intArrayOf(-1, u))
+        }
+        val res = IntArray(n)
+        for (i in 0 until n) {
+            res[i] = -1
+        }
+        res[0] = dfs(nexts, 0, -1)
+        val queue: Queue<Int> = LinkedList()
+        queue.add(0)
+        while (queue.isNotEmpty()) {
+            val index = queue.remove()
+            val `val` = res[index]
+            val next: List<IntArray> = nexts[index]
+            for (node in next) {
+                if (res[node[1]] == -1) {
+                    if (node[0] == 1) {
+                        res[node[1]] = `val` + 1
+                    } else {
+                        res[node[1]] = `val` - 1
+                    }
+                    queue.add(node[1])
+                }
+            }
+        }
+        return res
+    }
+
+    private fun dfs(nexts: Array<MutableList<IntArray>>, index: Int, pre: Int): Int {
+        var res = 0
+        val next: List<IntArray> = nexts[index]
+        for (node in next) {
+            if (node[1] != pre) {
+                if (node[0] == -1) {
+                    res++
+                }
+                res += dfs(nexts, node[1], index)
+            }
+        }
+        return res
+    }
+}
+```