LeetCode-in-Kotlin · javadev · Jan 13, 2023 · Jan 13, 2023
diff --git a/README.md b/README.md
@@ -45,6 +45,7 @@
 
 | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
 |-|-|-|-|-|-
+| 0496 |[Next Greater Element I](src/main/kotlin/g0401_0500/s0496_next_greater_element_i)| Easy | Array, Hash_Table, Stack, Monotonic_Stack | 171 | 100.00
 
 #### Day 6 Array
 
@@ -152,6 +153,7 @@
 
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 |-|-|-|-|-|-
+| 0503 |[Next Greater Element II](src/main/kotlin/g0501_0600/s0503_next_greater_element_ii)| Medium | Array, Stack, Monotonic_Stack | 331 | 92.68
 
 #### Day 11
 
@@ -338,6 +340,7 @@
 
 | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
 |-|-|-|-|-|-
+| 0511 |[Game Play Analysis I](src/main/kotlin/g0501_0600/s0511_game_play_analysis_i)| Easy | LeetCode_Curated_SQL_70, Database | 790 | 45.04
 
 #### Day 9 Control of Flow
 
@@ -413,6 +416,7 @@
 
 | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
 |-|-|-|-|-|-
+| 0509 |[Fibonacci Number](src/main/kotlin/g0501_0600/s0509_fibonacci_number)| Easy | Dynamic_Programming, Math, Recursion, Memoization | 139 | 82.72
 | 0070 |[Climbing Stairs](src/main/kotlin/g0001_0100/s0070_climbing_stairs)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Math, Memoization | 127 | 97.06
 
 #### Day 11 Dynamic Programming
@@ -534,7 +538,7 @@
 
 | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
 |-|-|-|-|-|-
-| 0416 |[Partition Equal Subset Sum](src/main/kotlin/g0401_0500/s0416_partition_equal_subset_sum)| Medium | Top_100_Liked_Questions, Array, Dynamic_Programming | 509 | 57.56
+| 0416 |[Partition Equal Subset Sum](src/main/kotlin/g0401_0500/s0416_partition_equal_subset_sum)| Medium | Top_100_Liked_Questions, Array, Dynamic_Programming | 204 | 98.82
 | 0152 |[Maximum Product Subarray](src/main/kotlin/g0101_0200/s0152_maximum_product_subarray)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming | 253 | 88.42
 
 #### Day 14 Sliding Window/Two Pointer
@@ -743,6 +747,7 @@
 | 0152 |[Maximum Product Subarray](src/main/kotlin/g0101_0200/s0152_maximum_product_subarray)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming | 253 | 88.42
 | 0198 |[House Robber](src/main/kotlin/g0101_0200/s0198_house_robber)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming | 156 | 92.24
 | 0213 |[House Robber II](src/main/kotlin/g0201_0300/s0213_house_robber_ii)| Medium | Array, Dynamic_Programming | 257 | 59.62
+| 0509 |[Fibonacci Number](src/main/kotlin/g0501_0600/s0509_fibonacci_number)| Easy | Dynamic_Programming, Math, Recursion, Memoization | 139 | 82.72
 | 0070 |[Climbing Stairs](src/main/kotlin/g0001_0100/s0070_climbing_stairs)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Math, Memoization | 127 | 97.06
 | 0064 |[Minimum Path Sum](src/main/kotlin/g0001_0100/s0064_minimum_path_sum)| Medium | Top_100_Liked_Questions, Array, Dynamic_Programming, Matrix | 222 | 95.70
 | 0300 |[Longest Increasing Subsequence](src/main/kotlin/g0201_0300/s0300_longest_increasing_subsequence)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Binary_Search | 318 | 82.28
@@ -1460,6 +1465,7 @@
 
 | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
 |-|-|-|-|-|-
+| 0509 |[Fibonacci Number](src/main/kotlin/g0501_0600/s0509_fibonacci_number)| Easy | Dynamic_Programming, Math, Recursion, Memoization | 139 | 82.72
 
 #### Day 2
 
@@ -1607,7 +1613,31 @@
 | 0647 |[Palindromic Substrings](src/main/kotlin/g0601_0700/s0647_palindromic_substrings)| Medium | Top_100_Liked_Questions, String, Dynamic_Programming | 266 | 67.83
 | 0560 |[Subarray Sum Equals K](src/main/kotlin/g0501_0600/s0560_subarray_sum_equals_k)| Medium | Top_100_Liked_Questions, Array, Hash_Table, Prefix_Sum, Data_Structure_II_Day_5_Array | 692 | 53.27
 | 0543 |[Diameter of Binary Tree](src/main/kotlin/g0501_0600/s0543_diameter_of_binary_tree)| Easy | Top_100_Liked_Questions, Depth_First_Search, Tree, Binary_Tree, Level_2_Day_7_Tree, Udemy_Tree_Stack_Queue | 307 | 43.93
+| 0513 |[Find Bottom Left Tree Value](src/main/kotlin/g0501_0600/s0513_find_bottom_left_tree_value)| Medium | Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree | 190 | 88.24
+| 0511 |[Game Play Analysis I](src/main/kotlin/g0501_0600/s0511_game_play_analysis_i)| Easy | LeetCode_Curated_SQL_70, Database, SQL_I_Day_8_Function | 790 | 45.04
+| 0509 |[Fibonacci Number](src/main/kotlin/g0501_0600/s0509_fibonacci_number)| Easy | Dynamic_Programming, Math, Recursion, Memoization, Dynamic_Programming_I_Day_1, Level_1_Day_10_Dynamic_Programming, Udemy_Dynamic_Programming | 139 | 82.72
+| 0508 |[Most Frequent Subtree Sum](src/main/kotlin/g0501_0600/s0508_most_frequent_subtree_sum)| Medium | Hash_Table, Depth_First_Search, Tree, Binary_Tree | 246 | 80.00
+| 0507 |[Perfect Number](src/main/kotlin/g0501_0600/s0507_perfect_number)| Easy | Math | 172 | 81.82
+| 0506 |[Relative Ranks](src/main/kotlin/g0501_0600/s0506_relative_ranks)| Easy | Array, Sorting, Heap_Priority_Queue | 244 | 94.23
+| 0504 |[Base 7](src/main/kotlin/g0501_0600/s0504_base_7)| Easy | Math | 136 | 100.00
+| 0503 |[Next Greater Element II](src/main/kotlin/g0501_0600/s0503_next_greater_element_ii)| Medium | Array, Stack, Monotonic_Stack, Programming_Skills_II_Day_10 | 331 | 92.68
+| 0502 |[IPO](src/main/kotlin/g0501_0600/s0502_ipo)| Hard | Array, Sorting, Greedy, Heap_Priority_Queue | 799 | 54.55
+| 0501 |[Find Mode in Binary Search Tree](src/main/kotlin/g0501_0600/s0501_find_mode_in_binary_search_tree)| Easy | Depth_First_Search, Tree, Binary_Tree, Binary_Search_Tree | 235 | 86.67
+| 0500 |[Keyboard Row](src/main/kotlin/g0401_0500/s0500_keyboard_row)| Easy | Array, String, Hash_Table | 170 | 85.19
+| 0498 |[Diagonal Traverse](src/main/kotlin/g0401_0500/s0498_diagonal_traverse)| Medium | Array, Matrix, Simulation | 430 | 61.54
+| 0497 |[Random Point in Non-overlapping Rectangles](src/main/kotlin/g0401_0500/s0497_random_point_in_non_overlapping_rectangles)| Medium | Math, Binary_Search, Prefix_Sum, Ordered_Set, Randomized, Reservoir_Sampling | 759 | 100.00
+| 0496 |[Next Greater Element I](src/main/kotlin/g0401_0500/s0496_next_greater_element_i)| Easy | Array, Hash_Table, Stack, Monotonic_Stack, Programming_Skills_I_Day_5_Function | 171 | 100.00
+| 0495 |[Teemo Attacking](src/main/kotlin/g0401_0500/s0495_teemo_attacking)| Easy | Array, Simulation | 283 | 100.00
 | 0494 |[Target Sum](src/main/kotlin/g0401_0500/s0494_target_sum)| Medium | Top_100_Liked_Questions, Array, Dynamic_Programming, Backtracking | 308 | 89.61
+| 0493 |[Reverse Pairs](src/main/kotlin/g0401_0500/s0493_reverse_pairs)| Hard | Array, Binary_Search, Ordered_Set, Divide_and_Conquer, Segment_Tree, Binary_Indexed_Tree, Merge_Sort | 887 | 66.67
+| 0492 |[Construct the Rectangle](src/main/kotlin/g0401_0500/s0492_construct_the_rectangle)| Easy | Math | 202 | 88.89
+| 0491 |[Non-decreasing Subsequences](src/main/kotlin/g0401_0500/s0491_increasing_subsequences)| Medium | Array, Hash_Table, Bit_Manipulation, Backtracking | 499 | 100.00
+| 0488 |[Zuma Game](src/main/kotlin/g0401_0500/s0488_zuma_game)| Hard | String, Dynamic_Programming, Breadth_First_Search, Memoization | 1727 | 100.00
+| 0486 |[Predict the Winner](src/main/kotlin/g0401_0500/s0486_predict_the_winner)| Medium | Array, Dynamic_Programming, Math, Recursion, Game_Theory | 158 | 84.62
+| 0485 |[Max Consecutive Ones](src/main/kotlin/g0401_0500/s0485_max_consecutive_ones)| Easy | Array | 272 | 88.46
+| 0483 |[Smallest Good Base](src/main/kotlin/g0401_0500/s0483_smallest_good_base)| Hard | Math, Binary_Search | 164 | 100.00
+| 0482 |[License Key Formatting](src/main/kotlin/g0401_0500/s0482_license_key_formatting)| Easy | String | 234 | 87.18
+| 0481 |[Magical String](src/main/kotlin/g0401_0500/s0481_magical_string)| Medium | String, Two_Pointers | 124 | 100.00
 | 0480 |[Sliding Window Median](src/main/kotlin/g0401_0500/s0480_sliding_window_median)| Hard | Array, Hash_Table, Heap_Priority_Queue, Sliding_Window | 409 | 100.00
 | 0479 |[Largest Palindrome Product](src/main/kotlin/g0401_0500/s0479_largest_palindrome_product)| Hard | Math | 147 | 100.00
 | 0478 |[Generate Random Point in a Circle](src/main/kotlin/g0401_0500/s0478_generate_random_point_in_a_circle)| Medium | Math, Geometry, Randomized, Rejection_Sampling | 862 | 100.00
@@ -1661,7 +1691,7 @@
 | 0420 |[Strong Password Checker](src/main/kotlin/g0401_0500/s0420_strong_password_checker)| Hard | String, Greedy, Heap_Priority_Queue | 157 | 80.00
 | 0419 |[Battleships in a Board](src/main/kotlin/g0401_0500/s0419_battleships_in_a_board)| Medium | Array, Depth_First_Search, Matrix | 273 | 76.92
 | 0417 |[Pacific Atlantic Water Flow](src/main/kotlin/g0401_0500/s0417_pacific_atlantic_water_flow)| Medium | Array, Depth_First_Search, Breadth_First_Search, Matrix, Graph_Theory_I_Day_4_Matrix_Related_Problems, Level_2_Day_10_Graph/BFS/DFS, Udemy_Graph | 319 | 100.00
-| 0416 |[Partition Equal Subset Sum](src/main/kotlin/g0401_0500/s0416_partition_equal_subset_sum)| Medium | Top_100_Liked_Questions, Array, Dynamic_Programming, Level_2_Day_13_Dynamic_Programming | 509 | 57.56
+| 0416 |[Partition Equal Subset Sum](src/main/kotlin/g0401_0500/s0416_partition_equal_subset_sum)| Medium | Top_100_Liked_Questions, Array, Dynamic_Programming, Level_2_Day_13_Dynamic_Programming | 204 | 98.82
 | 0415 |[Add Strings](src/main/kotlin/g0401_0500/s0415_add_strings)| Easy | String, Math, Simulation, Data_Structure_II_Day_6_String | 296 | 76.00
 | 0414 |[Third Maximum Number](src/main/kotlin/g0401_0500/s0414_third_maximum_number)| Easy | Array, Sorting | 317 | 73.00
 | 0413 |[Arithmetic Slices](src/main/kotlin/g0401_0500/s0413_arithmetic_slices)| Medium | Array, Dynamic_Programming, Algorithm_II_Day_14_Dynamic_Programming, Dynamic_Programming_I_Day_10 | 156 | 100.00

diff --git a/src/main/kotlin/g0401_0500/s0416_partition_equal_subset_sum/readme.md b/src/main/kotlin/g0401_0500/s0416_partition_equal_subset_sum/readme.md
@@ -33,36 +33,22 @@ Given a **non-empty** array `nums` containing **only positive integers**, find i
 ```kotlin
 class Solution {
     fun canPartition(nums: IntArray): Boolean {
-        var sum = 0
+        var sums = 0
         for (num in nums) {
-            sum += num
+            sums += num
         }
-        if (sum % 2 != 0) {
+        if (sums % 2 == 1) {
             return false
         }
-        sum /= 2
-        // if use primitive boolean array will make default value to false
-        // we need the default value "null" to help us to do the memo
-        val dp = arrayOfNulls<Boolean>(sum + 1)
-        return sumTo(nums, sum, 0, dp)
-    }
-
-    private fun sumTo(nums: IntArray, sum: Int, index: Int, dp: Array<Boolean?>): Boolean {
-        if (sum == 0) {
-            return true
-        }
-        if (sum < 0) {
-            return false
-        }
-        if (index == nums.size) {
-            return false
-        }
-        if (dp[sum] != null) {
-            return dp[sum]!!
+        sums /= 2
+        val dp = BooleanArray(sums + 1)
+        dp[0] = true
+        for (num in nums) {
+            for (sum in sums downTo num) {
+                dp[sum] = dp[sum] || dp[sum - num]
+            }
         }
-        // use the number or not use the number
-        dp[sum] = sumTo(nums, sum - nums[index], index + 1, dp) || sumTo(nums, sum, index + 1, dp)
-        return dp[sum]!!
+        return dp[sums]
     }
 }
 ```
diff --git a/src/main/kotlin/g0401_0500/s0430_flatten_a_multilevel_doubly_linked_list/readme.md b/src/main/kotlin/g0401_0500/s0430_flatten_a_multilevel_doubly_linked_list/readme.md
@@ -65,8 +65,6 @@ Merging the serialization of each level and removing trailing nulls we obtain:
 ## Solution
 
 ```kotlin
-import com_github_leetcode.prev_next.Node
-
 /*
  * Definition for a Node.
  * class Node(var `val`: Int) {

diff --git a/src/main/kotlin/g0401_0500/s0481_magical_string/readme.md b/src/main/kotlin/g0401_0500/s0481_magical_string/readme.md
@@ -0,0 +1,59 @@
+[![](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)
+
+## 481\. Magical String
+
+Medium
+
+A magical string `s` consists of only `'1'` and `'2'` and obeys the following rules:
+
+*   The string s is magical because concatenating the number of contiguous occurrences of characters `'1'` and `'2'` generates the string `s` itself.
+
+The first few elements of `s` is `s = "1221121221221121122……"`. If we group the consecutive `1`'s and `2`'s in `s`, it will be `"1 22 11 2 1 22 1 22 11 2 11 22 ......"` and the occurrences of `1`'s or `2`'s in each group are `"1 2 2 1 1 2 1 2 2 1 2 2 ......"`. You can see that the occurrence sequence is `s` itself.
+
+Given an integer `n`, return the number of `1`'s in the first `n` number in the magical string `s`.
+
+**Example 1:**
+
+**Input:** n = 6
+
+**Output:** 3
+
+**Explanation:** The first 6 elements of magical string s is "122112" and it contains three 1's, so return 3.
+
+**Example 2:**
+
+**Input:** n = 1
+
+**Output:** 1
+
+**Constraints:**
+
+*   <code>1 <= n <= 10<sup>5</sup></code>
+
+## Solution
+
+```kotlin
+class Solution {
+    fun magicalString(n: Int): Int {
+        val a = IntArray(n + 2)
+        var fast = 1
+        var slow = 1
+        var num = 1
+        while (fast <= n) {
+            a[fast++] = num
+            if (a[slow++] == 2) {
+                a[fast++] = num
+            }
+            num = 3 - num
+        }
+        var count = 0
+        for (j in 1..n) {
+            if (a[j] == 1) {
+                count++
+            }
+        }
+        return count
+    }
+}
+```
diff --git a/src/main/kotlin/g0401_0500/s0482_license_key_formatting/readme.md b/src/main/kotlin/g0401_0500/s0482_license_key_formatting/readme.md
@@ -0,0 +1,69 @@
+[![](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)
+
+## 482\. License Key Formatting
+
+Easy
+
+You are given a license key represented as a string `s` that consists of only alphanumeric characters and dashes. The string is separated into `n + 1` groups by `n` dashes. You are also given an integer `k`.
+
+We want to reformat the string `s` such that each group contains exactly `k` characters, except for the first group, which could be shorter than `k` but still must contain at least one character. Furthermore, there must be a dash inserted between two groups, and you should convert all lowercase letters to uppercase.
+
+Return _the reformatted license key_.
+
+**Example 1:**
+
+**Input:** s = "5F3Z-2e-9-w", k = 4
+
+**Output:** "5F3Z-2E9W"
+
+**Explanation:** The string s has been split into two parts, each part has 4 characters. Note that the two extra dashes are not needed and can be removed.
+
+**Example 2:**
+
+**Input:** s = "2-5g-3-J", k = 2
+
+**Output:** "2-5G-3J"
+
+**Explanation:** The string s has been split into three parts, each part has 2 characters except the first part as it could be shorter as mentioned above.
+
+**Constraints:**
+
+*   <code>1 <= s.length <= 10<sup>5</sup></code>
+*   `s` consists of English letters, digits, and dashes `'-'`.
+*   <code>1 <= k <= 10<sup>4</sup></code>
+
+## Solution
+
+```kotlin
+class Solution {
+    fun licenseKeyFormatting(s: String, k: Int): String {
+        val sb = StringBuilder()
+        var cnt = 0
+        var occ = 0
+        for (c in s.toCharArray()) {
+            if (c == '-') {
+                continue
+            }
+            cnt++
+        }
+        var l = cnt % k
+        for (c in s.toCharArray()) {
+            if (c == '-') {
+                continue
+            }
+            if (occ == k) {
+                occ = 0
+                sb.append('-')
+            } else if (occ == l && l != 0) {
+                l = 0
+                occ = 0
+                sb.append('-')
+            }
+            sb.append(c.uppercaseChar())
+            occ++
+        }
+        return sb.toString()
+    }
+}
+```
diff --git a/src/main/kotlin/g0401_0500/s0483_smallest_good_base/readme.md b/src/main/kotlin/g0401_0500/s0483_smallest_good_base/readme.md
@@ -0,0 +1,83 @@
+[![](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)
+
+## 483\. Smallest Good Base
+
+Hard
+
+Given an integer `n` represented as a string, return _the smallest **good base** of_ `n`.
+
+We call `k >= 2` a **good base** of `n`, if all digits of `n` base `k` are `1`'s.
+
+**Example 1:**
+
+**Input:** n = "13"
+
+**Output:** "3"
+
+**Explanation:** 13 base 3 is 111.
+
+**Example 2:**
+
+**Input:** n = "4681"
+
+**Output:** "8"
+
+**Explanation:** 4681 base 8 is 11111.
+
+**Example 3:**
+
+**Input:** n = "1000000000000000000"
+
+**Output:** "999999999999999999"
+
+**Explanation:** 1000000000000000000 base 999999999999999999 is 11.
+
+**Constraints:**
+
+*   `n` is an integer in the range <code>[3, 10<sup>18</sup>]</code>.
+*   `n` does not contain any leading zeros.
+
+## Solution
+
+```kotlin
+class Solution {
+    fun smallestGoodBase(n: String): String {
+        return sol1(n)
+    }
+
+    private fun sol1(n: String): String {
+        val x = n.toLong()
+        val ans: MutableList<Long> = ArrayList()
+        ans.add(x - 1)
+        val y = x - 1
+        for (i in 2..62) {
+            val dm = Math.pow(y.toDouble(), 1.0 / i)
+            val dml = dm.toLong()
+            var j = 0
+            while (j > -3 && dml + j > 1) {
+                val d = dml + j
+                if (y % d == 0L) {
+                    val poly = poly(d, i)
+                    if (poly == x) {
+                        ans.add(d)
+                    }
+                }
+                j--
+            }
+        }
+        val end = ans[ans.size - 1]
+        return end.toString()
+    }
+
+    private fun poly(b: Long, n: Int): Long {
+        var ans: Long = 1
+        var m: Long = 1
+        for (i in 0 until n) {
+            m *= b
+            ans += m
+        }
+        return ans
+    }
+}
+```