# LeetCode ✅😎😎

## How did I select the below questions?

Let's first focus on solving these questions. I selected them from various places including Udemy courses where they had marked these as popular questions. So, I'm sure these would help me a lot.

{% embed url="<https://docs.google.com/document/d/1SM92efk8oDl8nyVw8NHPnbGexTS9W-1gmTEYfEurLWQ/edit>" %}

## How to select Leetcode questions for interviews?&#x20;

### Read  Algo monster blog below

{% embed url="<https://leetcode.algo.monster/stop-leetcode-grind/?utm_source={google}&utm_term=leetcode&utm_campaign=leetcode_broad&utm_source=google&utm_term=leetcode&gclid=Cj0KCQjwwLKFBhDPARIsAPzPi-Ir9Mo4II5tmopqmSoxw-QSBfJkecfdZ85WUuW082PS3gLaTqcKbtcaAiz3EALw_wcB>" %}
Algo monster 1
{% endembed %}

{% embed url="<https://algo.monster/problems/google_online_assessment_questions>" %}
Algo monster 2
{% endembed %}

#### Questions I would solve. This list will increase as I go and I keep adding the new questions and also the info where I found it saying they are useful.

| Questions (E- Easy, M-Med, H-Hard)                       | Topics                                      | Who said this is important                                                                        |
| -------------------------------------------------------- | ------------------------------------------- | ------------------------------------------------------------------------------------------------- |
| 283 (E), 881(M), 941 (E), 11(M), 3(M), 34(M), 278(E)     | Arrays and Strings(Includes Google asked)   | Udemy <https://www.udemy.com/course/leetcode-in-python-50-algorithms-coding-interview-questions/> |
| 268(E), 204(E), 136(E), 657(E)                           | Math(Includes Microsoft asked)              |                                                                                                   |
| 1(E), 217(E), 169(E), 49(M), 454(M), 146(M), 76(H)       | Hashtables / Maps(Includes Facebook asked)  |                                                                                                   |
| 21(E), 141(E), 206(E), 2(M), 19(M), 328(M), 23(H)        | Linked List (Includes Amazon asked)         |                                                                                                   |
| 78(M), 17(M), 79(M), 39(M), 131(M)                       | Backtracking (Includes Uber asked)          |                                                                                                   |
| 101(E), 104(E), 112(E), 236(M), 230(M), 297(H), 124(H)   | Trees and Graphs(Includes Apple asked)      |                                                                                                   |
| 155(E), 20(E), 102(M), 103(M), 145(M)                    | Stacks and Queues(Includes Bloomberg asked) |                                                                                                   |
| 198(E), 121(E), 70(E), 322(M), 62(M), 5(M), 42(H), 42(H) | Dynamic Programming(Includes Google asked)  |                                                                                                   |

### Amazon LeetCode Questions (72 questions)

![Amazon leetcode questions](/files/-MaBCfMYB6XmF2nop1wA)

## Video Explanation&#x20;

### 1. Two Sum - Easy (Array)

{% embed url="<https://www.youtube.com/watch?v=U8B984M1VcU&ab_channel=TerribleWhiteboardTerribleWhiteboard>" %}
Two Sum
{% endembed %}

[`array`](https://leetcode.com/tag/array) | [`hash-table`](https://leetcode.com/tag/hash-table)

### 2. Add Two Numbers - Medium (Linked List)

{% embed url="<https://www.youtube.com/watch?v=1Spw7DEtB14&ab_channel=TerribleWhiteboard>" %}
Add Two Numbers
{% endembed %}

[`linked-list`](https://leetcode.com/tag/linked-list) | [`math`](https://leetcode.com/tag/math)

### 3. Longest Substring without repeating characters - Medium (Strings)

{% embed url="<https://www.youtube.com/watch?v=WKTgajDkVcA&ab_channel=TerribleWhiteboardTerribleWhiteboard>" %}

[`hash-table`](https://leetcode.com/tag/hash-table) | [`two-pointers`](https://leetcode.com/tag/two-pointers) | [`string`](https://leetcode.com/tag/string) | [`sliding-window`](https://leetcode.com/tag/sliding-window)

### 5. [Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring) And[ 647. Palindromic Substrings](https://www.youtube.com/watch?v=EIf9zFqufbU\&t=779s)

```javascript
const matrix = []
const str = "babad";
let count = 0;
let palindromes = [];
let longestPal = "" // longest palindromic substring

for (const ch of str) {
    matrix.push(new Array(str.length).fill(0))
}
//set diagonals to 1
for (let diag = 0; diag < str.length; diag++) {
    matrix[diag][diag] = 1
}

//set 1 in grid above diagonal
for (let col = 1; col < str.length; col++) {
    for (row = 0; row < col; row++) {
        if (row === col - 1 && str[row] === str[col]) {
            matrix[row][col] = 1
            count++;
            palindromes.push(str.slice(row, col + 1))
            if (str.slice(row, col + 1) > longestPal.length) {
                longestPal = str.slice(row, col + 1)
            }
        } else if (matrix[row + 1][col - 1] === 1 && str[row] === str[col]) {
            matrix[row][col] = 1
            count++;
            palindromes.push(str.slice(row, col + 1))
            if (str.slice(row, col + 1).length > longestPal.length) {
                longestPal = str.slice(row, col + 1)
            }
        }
    }
}
// (0,2) -> (1,1) -> (row=0,col=2) chk for (row=1,col=1)
const printMatrix = () => {
    for (let row = 0; row < str.length; row++) {
        let rowStr = ''
        for (let col = 0; col < str.length; col++) {
            rowStr += matrix[row][col] + (col !== str.length - 1 ? " | " : "")
        }
        console.log(`${row}       | ${rowStr} |`)
        console.log("-".repeat(23).padStart(30, " "))
    }
}

printMatrix()
console.log(palindromes) // all the palindromes
console.log(`The longest palindrome is ${longestPal}`) // longest palindrome
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://sandeepamaranath.gitbook.io/notes/data-structures/leetcode.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.