Today’s question is from Daily Leetcode Coding Challenge — March Edition. It is a medium-tagged question. Let us look into the problem statement.

**841****. Keys and Rooms**

There are `N`

rooms and you start in room `0`

. Each room has a distinct number in `0, 1, 2, ..., N-1`

, and each room may have some keys to access the next room.

Formally, each room `i`

has a list of keys `rooms[i]`

, and each key `rooms[i][j]`

is an integer in `[0, 1, ..., N-1]`

where `N = rooms.length`

. A key `rooms[i][j] = v`

opens the room with number `v`

.

Initially, all…

Today’s question is a SQL question. Let us look into the problem statement.

**196****. Delete Duplicate Emails**

Write a SQL query to **delete** all duplicate email entries in a table named `Person`

, keeping only unique emails based on its *smallest* **Id**.

`+----+------------------+`

| Id | Email |

+----+------------------+

| 1 | john@example.com |

| 2 | bob@example.com |

| 3 | john@example.com |

+----+------------------+

Id is the primary key column for this table.

For example, after running your query, the above `Person`

table should have the following rows:

`+----+------------------+`

| Id | Email…

Today’s question is a Math based question. It is taken from the Daily leetcode coding challenge- March edition. Let us look into the problem statement.

**478****. Generate Random Point in a Circle**

Given the radius and x-y positions of the center of a circle, write a function `randPoint`

which generates a uniform random point in the circle.

Note:

- input and output values are in floating-point.
- radius and x-y position of the center of the circle is passed into the class constructor.
- a point on the circumference of the circle is considered to be in the circle.
`randPoint`

returns a size…

Today’s question is from the Daily Leetcode coding challenge — March edition. Let us look into the problem statement.

**714****. Best Time to Buy and Sell Stock with Transaction Fee**

You are given an array `prices`

where `prices[i]`

is the price of a given stock on the `ith`

day, and an integer `fee`

representing a transaction fee.

Find the maximum profit you can achieve. You may complete as many transactions as you like, but you need to pay the transaction fee for each transaction.

**Note:** You may not engage in multiple transactions simultaneously (i.e., …

Today’s question is taken from the Daily Leetcode Coding challenge — March edition. Let us look into the problem statement.

**1721****. Swapping Nodes in a Linked List**

You are given the `head`

of a linked list, and an integer `k`

.

Return *the head of the linked list after **swapping** the values of the *`kth`

*node from the beginning and the *`kth`

*node from the end (the list is **1-indexed**).*

**Example 1:**

Today’s question is from Leetcode’s Daily coding Challenge- March Edition. Let us look into the problem statement.

**1461****. Check If a String Contains All Binary Codes of Size K**

Given a binary string `s`

and an integer `k`

.

Return *True* if every binary code of length `k`

is a substring of `s`

. Otherwise, return *False*.

**Example 1:**

**Input:** s = "00110110", k = 2

**Output:** true

**Explanation:** The binary codes of length 2 are "00", "01", "10" and "11". They can be all found as substrings at indicies 0, 1, 3 and 2 respectively.

**Example 2:**

**Input:** s = "00110"…

Today’s question is a Hard-tagged question on Leetcode. This question is quite frequently asked in technical interviews. Let us look into the problem statement.

**41****. First Missing Positive**

Given an unsorted integer array `nums`

, find the smallest missing positive integer.

**Example 1:**

**Input:** nums = [1,2,0]

**Output:** 3

**Example 2:**

**Input:** nums = [3,4,-1,1]

**Output:** 2

**Example 3:**

**Input:** nums = [7,8,9,11,12]

**Output:** 1

**Constraints:**

`0 <= nums.length <= 300`

`-231 <= nums[i] <= 231 - 1`

**Follow up:** Could you implement an algorithm that runs in `O(n)`

time and uses constant extra space?

This problem is a bit tricky…

Today’s question is a medium-tagged question in Leetcode. This question is asked in multiple coding interviews. Let us look into the problem statement.

**12****. Integer to Roman**

Roman numerals are represented by seven different symbols: `I`

, `V`

, `X`

, `L`

, `C`

, `D`

and `M`

.

**Symbol** **Value**

I 1

V 5

X 10

L 50

C 100

D 500

M 1000

For example, `2`

is written as `II`

in Roman numeral, just two one's added together. `12`

is written as `XII`

, which is simply `X + II`

. The number `27`

is written as `XXVII`

, which is `XX + V + II`

.

Roman…

Today’s question is a SQL question. Let us look into the problem statement.

**181****. Employees Earning More Than Their Managers**

The `Employee`

table holds all employees including their managers. Every employee has an Id, and there is also a column for the manager Id.

`+----+-------+--------+-----------+`

| Id | Name | Salary | ManagerId |

+----+-------+--------+-----------+

| 1 | Joe | 70000 | 3 |

| 2 | Henry | 80000 | 4 |

| 3 | Sam | 60000 | NULL |

| 4 | Max | 90000 | NULL |

+----+-------+--------+-----------+

Given the `Employee`

table, write a SQL query…

Today’s question is a medium-tagged question on leetcode. Let us look into the problem statement.

**247****. Strobogrammatic Number II**

Given an integer `n`

, return all the **strobogrammatic numbers** that are of length `n`

. You may return the answer in **any order**.

A **strobogrammatic number** is a number that looks the same when rotated `180`

degrees (looked at upside down).

**Example 1:**

**Input:** n = 2

**Output:** ["11","69","88","96"]

**Example 2:**

**Input:** n = 1

**Output:** ["0","1","8"]

**Constraints:**

`1 <= n <= 14`

Before we start with solving this problem, let us understand what strobogrammatic numbers are. A **strobogrammatic number** is a…

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