Added tasks 797-805

Author: javadev

README.md

@@ -58,6 +58,7 @@
 
 | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
 |-|-|-|-|-|-
+| 0797 |[All Paths From Source to Target](src/main/kotlin/g0701_0800/s0797_all_paths_from_source_to_target)| Medium | Depth_First_Search, Breadth_First_Search, Graph, Backtracking | 232 | 100.00
 
 #### Day 8 Standard Traversal
 
@@ -69,6 +70,7 @@
 
 | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
 |-|-|-|-|-|-
+| 0802 |[Find Eventual Safe States](src/main/kotlin/g0801_0900/s0802_find_eventual_safe_states)| Medium | Depth_First_Search, Breadth_First_Search, Graph, Topological_Sort | 511 | 100.00
 
 #### Day 10 Standard Traversal
 
@@ -1028,6 +1030,7 @@
 | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
 |-|-|-|-|-|-
 | 0130 |[Surrounded Regions](src/main/kotlin/g0101_0200/s0130_surrounded_regions)| Medium | Top_Interview_Questions, Array, Depth_First_Search, Breadth_First_Search, Matrix, Union_Find | 355 | 84.42
+| 0797 |[All Paths From Source to Target](src/main/kotlin/g0701_0800/s0797_all_paths_from_source_to_target)| Medium | Depth_First_Search, Breadth_First_Search, Graph, Backtracking | 232 | 100.00
 
 #### Day 9 Recursion Backtracking
 
@@ -1676,6 +1679,14 @@
 | 1143 |[Longest Common Subsequence](src/main/kotlin/g1101_1200/s1143_longest_common_subsequence)| Medium | Top_100_Liked_Questions, String, Dynamic_Programming, Algorithm_II_Day_17_Dynamic_Programming, Dynamic_Programming_I_Day_19, Udemy_Dynamic_Programming | 307 | 38.36
 | 0994 |[Rotting Oranges](src/main/kotlin/g0901_1000/s0994_rotting_oranges)| Medium | Array, Breadth_First_Search, Matrix, Algorithm_I_Day_9_Breadth_First_Search_Depth_First_Search, Level_2_Day_10_Graph/BFS/DFS | 308 | 57.93
 | 0864 |[Shortest Path to Get All Keys](src/main/kotlin/g0801_0900/s0864_shortest_path_to_get_all_keys)| Hard | Breadth_First_Search, Bit_Manipulation | 176 | 100.00
+| 0805 |[Split Array With Same Average](src/main/kotlin/g0801_0900/s0805_split_array_with_same_average)| Hard | Array, Dynamic_Programming, Math, Bit_Manipulation, Bitmask | 142 | 100.00
+| 0804 |[Unique Morse Code Words](src/main/kotlin/g0801_0900/s0804_unique_morse_code_words)| Easy | Array, String, Hash_Table | 158 | 80.00
+| 0803 |[Bricks Falling When Hit](src/main/kotlin/g0801_0900/s0803_bricks_falling_when_hit)| Hard | Array, Matrix, Union_Find | 742 | 100.00
+| 0802 |[Find Eventual Safe States](src/main/kotlin/g0801_0900/s0802_find_eventual_safe_states)| Medium | Depth_First_Search, Breadth_First_Search, Graph, Topological_Sort, Graph_Theory_I_Day_9_Standard_Traversal | 511 | 100.00
+| 0801 |[Minimum Swaps To Make Sequences Increasing](src/main/kotlin/g0801_0900/s0801_minimum_swaps_to_make_sequences_increasing)| Hard | Array, Dynamic_Programming | 617 | 83.33
+| 0799 |[Champagne Tower](src/main/kotlin/g0701_0800/s0799_champagne_tower)| Medium | Dynamic_Programming | 153 | 100.00
+| 0798 |[Smallest Rotation with Highest Score](src/main/kotlin/g0701_0800/s0798_smallest_rotation_with_highest_score)| Hard | Array, Prefix_Sum | 470 | 100.00
+| 0797 |[All Paths From Source to Target](src/main/kotlin/g0701_0800/s0797_all_paths_from_source_to_target)| Medium | Depth_First_Search, Breadth_First_Search, Graph, Backtracking, Algorithm_II_Day_8_Breadth_First_Search_Depth_First_Search, Graph_Theory_I_Day_7_Standard_Traversal | 232 | 100.00
 | 0796 |[Rotate String](src/main/kotlin/g0701_0800/s0796_rotate_string)| Easy | String, String_Matching | 134 | 100.00
 | 0795 |[Number of Subarrays with Bounded Maximum](src/main/kotlin/g0701_0800/s0795_number_of_subarrays_with_bounded_maximum)| Medium | Array, Two_Pointers | 361 | 66.67
 | 0794 |[Valid Tic-Tac-Toe State](src/main/kotlin/g0701_0800/s0794_valid_tic_tac_toe_state)| Medium | Array, String | 138 | 100.00

src/main/kotlin/g0401_0500/s0493_reverse_pairs/readme.md

@@ -46,8 +46,6 @@ A **reverse pair** is a pair `(i, j)` where:
 ## Solution
 
 ```kotlin
-import java.util.Arrays
-
 class Solution {
     fun reversePairs(nums: IntArray): Int {
         return mergeSort(nums, 0, nums.size - 1)
@@ -68,7 +66,7 @@ class Solution {
             }
             cnt += j - (mid + 1)
         }
-        Arrays.sort(nums, start, end + 1)
+        nums.sort(start, end + 1)
         return cnt
     }
 }

src/main/kotlin/g0701_0800/s0787_cheapest_flights_within_k_stops/readme.md

@@ -68,15 +68,13 @@ The optimal path with no stops from city 0 to 2 is marked in red and has cost 50
 ## Solution
 
 ```kotlin
-import java.util.Arrays
-
 class Solution {
     fun findCheapestPrice(n: Int, flights: Array<IntArray>, src: Int, dst: Int, k: Int): Int {
         // k + 2 becase there are total of k(intermediate stops) + 1(src) + 1(dst)
         // dp[i][j] = cost to reach j using atmost i edges from src
         val dp = Array(k + 2) { IntArray(n) }
         for (row in dp) {
-            Arrays.fill(row, Int.MAX_VALUE)
+            row.fill(Int.MAX_VALUE)
         }
         // cost to reach src is always 0
         for (i in 0..k + 1) {

src/main/kotlin/g0701_0800/s0797_all_paths_from_source_to_target/readme.md

@@ -0,0 +1,64 @@
+[![](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)
+
+## 797\. All Paths From Source to Target
+
+Medium
+
+Given a directed acyclic graph (**DAG**) of `n` nodes labeled from `0` to `n - 1`, find all possible paths from node `0` to node `n - 1` and return them in **any order**.
+
+The graph is given as follows: `graph[i]` is a list of all nodes you can visit from node `i` (i.e., there is a directed edge from node `i` to node `graph[i][j]`).
+
+**Example 1:**
+
+![](https://assets.leetcode.com/uploads/2020/09/28/all_1.jpg)
+
+**Input:** graph = \[\[1,2],[3],[3],[]]
+
+**Output:** [[0,1,3],[0,2,3]]
+
+**Explanation:** There are two paths: 0 -> 1 -> 3 and 0 -> 2 -> 3.
+
+**Example 2:**
+
+![](https://assets.leetcode.com/uploads/2020/09/28/all_2.jpg)
+
+**Input:** graph = \[\[4,3,1],[3,2,4],[3],[4],[]]
+
+**Output:** [[0,4],[0,3,4],[0,1,3,4],[0,1,2,3,4],[0,1,4]]
+
+**Constraints:**
+
+*   `n == graph.length`
+*   `2 <= n <= 15`
+*   `0 <= graph[i][j] < n`
+*   `graph[i][j] != i` (i.e., there will be no self-loops).
+*   All the elements of `graph[i]` are **unique**.
+*   The input graph is **guaranteed** to be a **DAG**.
+
+## Solution
+
+```kotlin
+class Solution {
+    private var res: MutableList<List<Int>>? = null
+    fun allPathsSourceTarget(graph: Array<IntArray>): List<List<Int>> {
+        res = ArrayList()
+        val temp: MutableList<Int> = ArrayList()
+        temp.add(0)
+        // perform DFS
+        solve(graph, temp, 0)
+        return res as ArrayList<List<Int>>
+    }
+
+    private fun solve(graph: Array<IntArray>, temp: MutableList<Int>, lastNode: Int) {
+        if (lastNode == graph.size - 1) {
+            res!!.add(ArrayList(temp))
+        }
+        for (link in graph[lastNode]) {
+            temp.add(link)
+            solve(graph, temp, link)
+            temp.removeAt(temp.size - 1)
+        }
+    }
+}
+```

src/main/kotlin/g0701_0800/s0798_smallest_rotation_with_highest_score/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)
+
+## 798\. Smallest Rotation with Highest Score
+
+Hard
+
+You are given an array `nums`. You can rotate it by a non-negative integer `k` so that the array becomes `[nums[k], nums[k + 1], ... nums[nums.length - 1], nums[0], nums[1], ..., nums[k-1]]`. Afterward, any entries that are less than or equal to their index are worth one point.
+
+*   For example, if we have `nums = [2,4,1,3,0]`, and we rotate by `k = 2`, it becomes `[1,3,0,2,4]`. This is worth `3` points because `1 > 0` [no points], `3 > 1` [no points], `0 <= 2` [one point], `2 <= 3` [one point], `4 <= 4` [one point].
+
+Return _the rotation index_ `k` _that corresponds to the highest score we can achieve if we rotated_ `nums` _by it_. If there are multiple answers, return the smallest such index `k`.
+
+**Example 1:**
+
+**Input:** nums = [2,3,1,4,0]
+
+**Output:** 3
+
+**Explanation:** Scores for each k are listed below:
+
+k = 0, nums = [2,3,1,4,0], score 2
+
+k = 1, nums = [3,1,4,0,2], score 3
+
+k = 2, nums = [1,4,0,2,3], score 3 
+
+k = 3, nums = [4,0,2,3,1], score 4 
+
+k = 4, nums = [0,2,3,1,4], score 3 So we should choose 
+
+k = 3, which has the highest score.
+
+**Example 2:**
+
+**Input:** nums = [1,3,0,2,4]
+
+**Output:** 0
+
+**Explanation:** nums will always have 3 points no matter how it shifts. So we will choose the smallest k, which is 0.
+
+**Constraints:**
+
+*   <code>1 <= nums.length <= 10<sup>5</sup></code>
+*   `0 <= nums[i] < nums.length`
+
+## Solution
+
+```kotlin
+class Solution {
+    // nums[i] will be in the range [0, nums.length].
+    // At which positions will we lose points? The answer is k = i - nums[i] + 1.
+    // We need to accumulate points we have lost from previous rotations using prefix sum except one
+    // we did not lose.
+    fun bestRotation(nums: IntArray): Int {
+        val n = nums.size
+        var res = 0
+        val change = IntArray(n)
+        for (i in 0 until n) {
+            change[(i - nums[i] + 1 + n) % n]--
+        }
+        for (i in 1 until n) {
+            change[i] += change[i - 1] + 1
+            res = if (change[i] > change[res]) i else res
+        }
+        return res
+    }
+}
+```

src/main/kotlin/g0701_0800/s0799_champagne_tower/readme.md

@@ -0,0 +1,80 @@
+[![](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)
+
+## 799\. Champagne Tower
+
+Medium
+
+We stack glasses in a pyramid, where the **first** row has `1` glass, the **second** row has `2` glasses, and so on until the 100<sup>th</sup> row. Each glass holds one cup of champagne.
+
+Then, some champagne is poured into the first glass at the top. When the topmost glass is full, any excess liquid poured will fall equally to the glass immediately to the left and right of it. When those glasses become full, any excess champagne will fall equally to the left and right of those glasses, and so on. (A glass at the bottom row has its excess champagne fall on the floor.)
+
+For example, after one cup of champagne is poured, the top most glass is full. After two cups of champagne are poured, the two glasses on the second row are half full. After three cups of champagne are poured, those two cups become full - there are 3 full glasses total now. After four cups of champagne are poured, the third row has the middle glass half full, and the two outside glasses are a quarter full, as pictured below.
+
+![](https://s3-lc-upload.s3.amazonaws.com/uploads/2018/03/09/tower.png)
+
+Now after pouring some non-negative integer cups of champagne, return how full the <code>j<sup>th</sup></code> glass in the <code>i<sup>th</sup></code> row is (both `i` and `j` are 0-indexed.)
+
+**Example 1:**
+
+**Input:** poured = 1, query\_row = 1, query\_glass = 1
+
+**Output:** 0.00000
+
+**Explanation:** We poured 1 cup of champange to the top glass of the tower (which is indexed as (0, 0)). There will be no excess liquid so all the glasses under the top glass will remain empty.
+
+**Example 2:**
+
+**Input:** poured = 2, query\_row = 1, query\_glass = 1
+
+**Output:** 0.50000
+
+**Explanation:** We poured 2 cups of champange to the top glass of the tower (which is indexed as (0, 0)). There is one cup of excess liquid. The glass indexed as (1, 0) and the glass indexed as (1, 1) will share the excess liquid equally, and each will get half cup of champange.
+
+**Example 3:**
+
+**Input:** poured = 100000009, query\_row = 33, query\_glass = 17
+
+**Output:** 1.00000
+
+**Constraints:**
+
+*   <code>0 <= poured <= 10<sup>9</sup></code>
+*   `0 <= query_glass <= query_row < 100`
+
+## Solution
+
+```kotlin
+class Solution {
+    fun champagneTower(poured: Int, queryRow: Int, queryGlass: Int): Double {
+        var curRow = 0
+        // first row
+        var cur = doubleArrayOf(poured.toDouble())
+        // second row
+        var next = DoubleArray(2)
+        var spilled: Boolean
+        do {
+            spilled = false
+            for (i in cur.indices) {
+                // spilling, put the excess into the next row.
+                if (cur[i] > 1) {
+                    val spilledAmount = cur[i] - 1
+                    cur[i] = 1.0
+                    next[i] += spilledAmount / 2
+                    next[i + 1] = spilledAmount / 2
+                    spilled = true
+                }
+            }
+            // got to the desired row, return the glass amount
+            if (curRow == queryRow) {
+                return cur[queryGlass]
+            }
+            cur = next
+            curRow++
+            next = DoubleArray(curRow + 2)
+        } while (spilled)
+        // spill did not happen to the desired row
+        return 0.0
+    }
+}
+```

src/main/kotlin/g0801_0900/s0801_minimum_swaps_to_make_sequences_increasing/readme.md

@@ -0,0 +1,60 @@
+[![](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)
+
+## 801\. Minimum Swaps To Make Sequences Increasing
+
+Hard
+
+You are given two integer arrays of the same length `nums1` and `nums2`. In one operation, you are allowed to swap `nums1[i]` with `nums2[i]`.
+
+*   For example, if <code>nums1 = [1,2,3,<ins>8</ins>]</code>, and <code>nums2 = [5,6,7,<ins>4</ins>]</code>, you can swap the element at `i = 3` to obtain `nums1 = [1,2,3,4]` and `nums2 = [5,6,7,8]`.
+
+Return _the minimum number of needed operations to make_ `nums1` _and_ `nums2` _**strictly increasing**_. The test cases are generated so that the given input always makes it possible.
+
+An array `arr` is **strictly increasing** if and only if `arr[0] < arr[1] < arr[2] < ... < arr[arr.length - 1]`.
+
+**Example 1:**
+
+**Input:** nums1 = [1,3,5,4], nums2 = [1,2,3,7]
+
+**Output:** 1
+
+**Explanation:** Swap nums1[3] and nums2[3]. Then the sequences are: nums1 = [1, 3, 5, 7] and nums2 = [1, 2, 3, 4] which are both strictly increasing.
+
+**Example 2:**
+
+**Input:** nums1 = [0,3,5,8,9], nums2 = [2,1,4,6,9]
+
+**Output:** 1
+
+**Constraints:**
+
+*   <code>2 <= nums1.length <= 10<sup>5</sup></code>
+*   `nums2.length == nums1.length`
+*   <code>0 <= nums1[i], nums2[i] <= 2 * 10<sup>5</sup></code>
+
+## Solution
+
+```kotlin
+class Solution {
+    fun minSwap(listA: IntArray, listB: IntArray): Int {
+        val dp = IntArray(2)
+        dp[1] = 1
+        for (i in 1 until listA.size) {
+            var a = Int.MAX_VALUE
+            var b = Int.MAX_VALUE
+            if (listA[i] > listA[i - 1] && listB[i] > listB[i - 1]) {
+                a = dp[0]
+                b = dp[1]
+            }
+            if (listA[i] > listB[i - 1] && listB[i] > listA[i - 1]) {
+                a = a.coerceAtMost(dp[1])
+                b = b.coerceAtMost(dp[0])
+            }
+            dp[0] = a
+            dp[1] = b + 1
+        }
+        return dp[0].coerceAtMost(dp[1])
+    }
+}
+```