Added task 3497

Author: javadev

README.md

@@ -2088,6 +2088,7 @@
 
 | #    |      Title     | Difficulty  | Tag         | Time, ms | Time, %
 |------|----------------|-------------|-------------|----------|--------
+| 3497 |[Analyze Subscription Conversion](src/main/kotlin/g3401_3500/s3497_analyze_subscription_conversion)| Medium | Database | 347 | 100.00
 | 3495 |[Minimum Operations to Make Array Elements Zero](src/main/kotlin/g3401_3500/s3495_minimum_operations_to_make_array_elements_zero)| Hard | Array, Math, Bit_Manipulation | 12 | 100.00
 | 3494 |[Find the Minimum Amount of Time to Brew Potions](src/main/kotlin/g3401_3500/s3494_find_the_minimum_amount_of_time_to_brew_potions)| Medium | Array, Simulation, Prefix_Sum | 70 | 100.00
 | 3493 |[Properties Graph](src/main/kotlin/g3401_3500/s3493_properties_graph)| Medium | Array, Hash_Table, Depth_First_Search, Breadth_First_Search, Graph, Union_Find | 45 | 100.00

src/main/kotlin/g0801_0900/s0855_exam_room/readme.md

@@ -90,7 +90,7 @@ class ExamRoom() {
         var maxAtLeft: Node? = null
         var cur = tail.pre
         while (cur !== head && cur!!.pre !== head) {
-            val pre = cur!!.pre
+            val pre = cur.pre
             val at = (cur.`val` + pre!!.`val`) / 2
             val distance = at - pre.`val`
             if (distance >= max) {

src/main/kotlin/g1101_1200/s1171_remove_zero_sum_consecutive_nodes_from_linked_list/readme.md

@@ -65,7 +65,7 @@ class Solution {
                     curr = curr!!.next
                     key += curr!!.`val`
                 }
-                map.getValue(preSum).next = curr!!.next
+                map.getValue(preSum).next = curr.next
             } else {
                 map[preSum] = curr
             }

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

@@ -40,7 +40,6 @@ It can be shown that there are no other pairs with equal maximum digits, so the
 
 ```kotlin
 import java.util.PriorityQueue
-import kotlin.collections.HashMap
 import kotlin.math.max
 
 @Suppress("NAME_SHADOWING")

src/main/kotlin/g3201_3300/s3273_minimum_amount_of_damage_dealt_to_bob/readme.md

@@ -74,8 +74,8 @@ class Solution {
     }
 
     internal class Pair(var key: Int, var `val`: Int) : Comparable<Pair> {
-        override fun compareTo(p: Pair): Int {
-            return `val` * p.key - key * p.`val`
+        override fun compareTo(other: Pair): Int {
+            return `val` * other.key - key * other.`val`
         }
     }
 }

src/main/kotlin/g3301_3400/s3321_find_x_sum_of_all_k_long_subarrays_ii/readme.md

@@ -62,11 +62,11 @@ class Solution {
             cnt = c
         }
 
-        override fun compareTo(o: RC): Int {
-            if (cnt != o.cnt) {
-                return cnt - o.cnt
+        override fun compareTo(other: RC): Int {
+            if (cnt != other.cnt) {
+                return cnt - other.cnt
             }
-            return `val` - o.`val`
+            return `val` - other.`val`
         }
     }
 

src/main/kotlin/g3301_3400/s3382_maximum_area_rectangle_with_point_constraints_ii/readme.md

@@ -102,8 +102,8 @@ class Solution {
     }
 
     private class Pair(val x: Int, val y: Int) : Comparable<Pair> {
-        override fun compareTo(p: Pair): Int {
-            return if (x == p.x) y - p.y else x - p.x
+        override fun compareTo(other: Pair): Int {
+            return if (x == other.x) y - other.y else x - other.x
         }
     }
 }

src/main/kotlin/g3401_3500/s3497_analyze_subscription_conversion/readme.md

@@ -0,0 +1,114 @@
+[![](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)
+
+## 3497\. Analyze Subscription Conversion
+
+Medium
+
+Table: `UserActivity`
+
+    +------------------+---------+
+    | Column Name      | Type    |
+    +------------------+---------+
+    | user_id          | int     |
+    | activity_date    | date    |
+    | activity_type    | varchar |
+    | activity_duration| int     |
+    +------------------+---------+
+    (user_id, activity_date, activity_type) is the unique key for this table. activity_type is one of ('free_trial', 'paid', 'cancelled').
+    activity_duration is the number of minutes the user spent on the platform that day.
+    Each row represents a user's activity on a specific date. 
+
+A subscription service wants to analyze user behavior patterns. The company offers a `7`\-day **free trial**, after which users can subscribe to a **paid plan** or **cancel**. Write a solution to:
+
+1.  Find users who converted from free trial to paid subscription
+2.  Calculate each user's **average daily activity duration** during their **free trial** period (rounded to `2` decimal places)
+3.  Calculate each user's **average daily activity duration** during their **paid** subscription period (rounded to `2` decimal places)
+
+Return _the result table ordered by_ `user_id` _in **ascending** order_.
+
+The result format is in the following example.
+
+**Example:**
+
+**Input:**
+
+UserActivity table:
+
+| user_id | activity_date | activity_type | activity_duration |
+|---------|---------------|---------------|-------------------|
+| 1       | 2023-01-01    | free_trial    | 45                |
+| 1       | 2023-01-02    | free_trial    | 30                |
+| 1       | 2023-01-05    | free_trial    | 60                |
+| 1       | 2023-01-10    | paid          | 75                |
+| 1       | 2023-01-12    | paid          | 90                |
+| 1       | 2023-01-15    | paid          | 65                |
+| 2       | 2023-02-01    | free_trial    | 55                |
+| 2       | 2023-02-03    | free_trial    | 25                |
+| 2       | 2023-02-07    | free_trial    | 50                |
+| 2       | 2023-02-10    | cancelled     | 0                 |
+| 3       | 2023-03-05    | free_trial    | 70                |
+| 3       | 2023-03-06    | free_trial    | 60                |
+| 3       | 2023-03-08    | free_trial    | 80                |
+| 3       | 2023-03-12    | paid          | 50                |
+| 3       | 2023-03-15    | paid          | 55                |
+| 3       | 2023-03-20    | paid          | 85                |
+| 4       | 2023-04-01    | free_trial    | 40                |
+| 4       | 2023-04-03    | free_trial    | 35                |
+| 4       | 2023-04-05    | paid          | 45                |
+| 4       | 2023-04-07    | cancelled     | 0                 |
+
+**Output:**
+
+| user_id | trial_avg_duration | paid_avg_duration |
+|---------|--------------------|-------------------|
+| 1       | 45.00              | 76.67             |
+| 3       | 70.00              | 63.33             |
+| 4       | 37.50              | 45.00             |
+
+**Explanation:**
+
+*   **User 1:**
+    *   Had 3 days of free trial with durations of 45, 30, and 60 minutes.
+    *   Average trial duration: (45 + 30 + 60) / 3 = 45.00 minutes.
+    *   Had 3 days of paid subscription with durations of 75, 90, and 65 minutes.
+    *   Average paid duration: (75 + 90 + 65) / 3 = 76.67 minutes.
+*   **User 2:**
+    *   Had 3 days of free trial with durations of 55, 25, and 50 minutes.
+    *   Average trial duration: (55 + 25 + 50) / 3 = 43.33 minutes.
+    *   Did not convert to a paid subscription (only had free\_trial and cancelled activities).
+    *   Not included in the output because they didn't convert to paid.
+*   **User 3:**
+    *   Had 3 days of free trial with durations of 70, 60, and 80 minutes.
+    *   Average trial duration: (70 + 60 + 80) / 3 = 70.00 minutes.
+    *   Had 3 days of paid subscription with durations of 50, 55, and 85 minutes.
+    *   Average paid duration: (50 + 55 + 85) / 3 = 63.33 minutes.
+*   **User 4:**
+    *   Had 2 days of free trial with durations of 40 and 35 minutes.
+    *   Average trial duration: (40 + 35) / 2 = 37.50 minutes.
+    *   Had 1 day of paid subscription with duration of 45 minutes before cancelling.
+    *   Average paid duration: 45.00 minutes.
+
+The result table only includes users who converted from free trial to paid subscription (users 1, 3, and 4), and is ordered by user\_id in ascending order.
+
+## Solution
+
+```sql
+# Write your MySQL query statement below
+SELECT
+    ft.user_id,
+    ROUND(ft.avg_trial, 2) AS trial_avg_duration,
+    ROUND(pt.avg_paid, 2) AS paid_avg_duration
+FROM
+    (SELECT user_id, AVG(activity_duration) AS avg_trial
+     FROM UserActivity
+     WHERE activity_type = 'free_trial'
+     GROUP BY user_id) ft
+JOIN
+    (SELECT user_id, AVG(activity_duration) AS avg_paid
+     FROM UserActivity
+     WHERE activity_type = 'paid'
+     GROUP BY user_id) pt
+ON ft.user_id = pt.user_id
+ORDER BY ft.user_id ASC;
+```