DSA Crash Course [Part 32] - Reverse List Approach

In this lesson, Alvin explores the strategy to solving the following interview problem:

> Write a function, *reverse_list*, that takes in the head of a linked list as an argument. The function should reverse the order of the nodes in the linked list **in-place** and return the new head of the reversed linked list.

```
a = Node("a")
b = Node("b")
c = Node("c")
d = Node("d")
e = Node("e")
f = Node("f")
a.next = b
b.next = c
c.next = d
d.next = e
e.next = f

# a -> b -> c -> d -> e -> f
reverse_list(a) # f -> e -> d -> c -> b -> a
```

```
x = Node("x")
y = Node("y")
x.next = y

# x -> y
reverse_list(x) # y -> x
```

```
p = Node("p")

# p
reverse_list(p) # p
```

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 31] - Get Node Value Walkthrough

In this lesson, Alvin walks through the python implementation for the *get_node_value* problem.

Code along and test your work in the following editor workspace: <https://structy.net/problems/get-node-value?language=py>

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 30] - Get Node Value Approach

In this lesson, Alvin explores the strategy to solving the following interview problem:

> Write a function, *get_node_value*, that takes in the head of a linked list and an index. The function should return the value of the linked list at the specified index.
>
> If there is no node at the given index, then return *None*.

```
a = Node("a")
b = Node("b")
c = Node("c")
d = Node("d")
a.next = b
b.next = c
c.next = d

# a -> b -> c -> d
get_node_value(a, 2) # 'c'
```

```
a = Node("a")
b = Node("b")
c = Node("c")
d = Node("d")
a.next = b
b.next = c
c.next = d

# a -> b -> c -> d
get_node_value(a, 3) # 'd'
```

```
a = Node("a")
b = Node("b")
c = Node("c")
d = Node("d")
a.next = b
b.next = c
c.next = d

# a -> b -> c -> d
get_node_value(a, 7) # None
```

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 29] - Linked List Find Walkthrough

In this lesson, Alvin walks through the python implementation for the *linked_list_find* problem.

Code along and test your work in the following editor workspace: <https://structy.net/problems/linked-list-find?language=py>

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 28] - Linked List Find Approach

In this lesson, Alvin explores the strategy to solving the following interview problem:

> Write a function, *linked_list_find*, that takes in the head of a linked list and a target value. The function should return a boolean indicating whether or not the linked list contains the target.

```
a = Node("a")
b = Node("b")
c = Node("c")
d = Node("d")
a.next = b
b.next = c
c.next = d

# a -> b -> c -> d
linked_list_find(a, "c") # True
```

```
a = Node("a")
b = Node("b")
c = Node("c")
d = Node("d")
a.next = b
b.next = c
c.next = d

# a -> b -> c -> d
linked_list_find(a, "d") # True
```

```
a = Node("a")
b = Node("b")
c = Node("c")
d = Node("d")
a.next = b
b.next = c
c.next = d

# a -> b -> c -> d
linked_list_find(a, "q") # False
```

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 27] - Sum List Walkthrough

In this lesson, Alvin walks through the python implementation for the *sum_list* problem.

Code along and test your work in the following editor workspace: <https://structy.net/problems/sum-list?language=py>

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 26] - Sum List Approach

In this lesson, Alvin explores the strategy to solving the following interview problem:

> Write a function, *sum_list*, that takes in the head of a linked list containing numbers as an argument. The function should return the total sum of all values in the linked list.

```
a = Node(2)
b = Node(8)
c = Node(3)
d = Node(-1)
e = Node(7)
a.next = b
b.next = c
c.next = d
d.next = e

# 2 -> 8 -> 3 -> -1 -> 7
sum_list(a) # 19
```

```
x = Node(38)
y = Node(4)
x.next = y

# 38 -> 4
sum_list(x) # 42
```

```
z = Node(100)

# 100
sum_list(z) # 100
```

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 25] - Linked List Values Walkthrough

In this lesson, Alvin walks through the python implementation for the *linked_list_values* problem.

Code along and test your work in the following editor workspace: <https://structy.net/problems/linked-list-values?language=py>

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 24] - Linked List Values Approach

In this lesson, Alvin explores the strategy to solving the following interview problem:

> Write a function, *linked_list_values*, that takes in the head of a linked list as an argument. The function should return a list containing all values of the nodes in the linked list.

```
a = Node("a")
b = Node("b")
c = Node("c")
d = Node("d")
a.next = b
b.next = c
c.next = d

# a -> b -> c -> d

linked_list_values(a) # -> [ 'a', 'b', 'c', 'd' ]
```

```
x = Node("x")
y = Node("y")
x.next = y

# x -> y

linked_list_values(x) # -> [ 'x', 'y' ]
```

```
q = Node("q")

# q

linked_list_values(q) # -> [ 'q' ]
```

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 23] - Linked List Warm Up Lecture

In this lecture, Alvin goes over how to implement a linked list in python.

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 22] - Linked List Intro Lecture

In this lecture, Alvin explains the basic structure of a singly-linked list.

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 21] - Sum Numbers Recursive Walkthrough

In this lesson, Alvin walks through the python implementation for the *sum_numbers_recursive* problem.

Code along and test your work in the following editor workspace: <https://structy.net/problems/sum-numbers-recursive?language=py>

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 20] - Sum Numbers Recursive Approach

In this lesson, Alvin explores the strategy to solving the following interview problem:

> Write a function *sum_numbers_recursive* that takes in an array of numbers and returns the sum of all the numbers in the array. All elements will be integers. Solve this recursively.

```
sum_numbers_recursive([5, 2, 9, 10]); # -> 26
```

```
sum_numbers_recursive([1, -1, 1, -1, 1, -1, 1]); # -> 1
```

```
sum_numbers_recursive([]); # -> 0
```

```
sum_numbers_recursive([1000, 0, 0, 0, 0, 0, 1]); # -> 1001
```

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 19] - Recursion Warm Up Lecture

In this lecture, Alvin explains some basic recursive function examples.

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 18] - Recursion Intro Lecture

In this lecture, Alvin introduces the mental model we should use when applying recursion.

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 17] - Intersection Walkthrough

In this lesson, Alvin walks through the python implementation for the *intersection* problem.

Code along and test your work in the following editor workspace: <https://structy.net/problems/intersection?language=py>

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 16] - Intersection Approach

In this lesson, Alvin explores the strategy to solving the following interview problem:

> Write a function, *intersection*, that takes in two lists, *a*,\_b\_, as arguments. The function should return a new list containing elements that are in both of the two lists.
>
> You may assume that each input list does not contain duplicate elements.

```
intersection([4,2,1,6], [3,6,9,2,10]) # -> [2,6]
```

```
intersection([2,4,6], [4,2]) # -> [2,4]
```

```
intersection([4,2,1], [1,2,4,6]) # -> [1,2,4]
```

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 15] - Pair Product Walkthrough

In this lesson, Alvin walks through the python implementation for the *pair_product* problem.

Code along and test your work in the following editor workspace: <https://structy.net/problems/pair-product?language=py>

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 14] - Pair Product Approach

In this lesson, Alvin explores the strategy to solving the following interview problem:

> Write a function, *pair_product*, that takes in a list and a target product as arguments. The function should return a tuple containing a pair of indices whose elements multiply to the given target. The indices returned must be unique.
>
> Be sure to return the indices, not the elements themselves.
>
> There is guaranteed to be one such pair whose product is the target.

```
pair_product([3, 2, 5, 4, 1], 8) # -> (1, 3)
```

```
pair_product([3, 2, 5, 4, 1], 10) # -> (1, 2)
```

```
pair_product([4, 7, 9, 2, 5, 1], 5) # -> (4, 5)
```

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

DSA Crash Course [Part 13] - Pair Sum Walkthrough

In this lesson, Alvin walks through the python implementation for the *pair_sum* problem.

Code along and test your work in the following editor workspace: <https://structy.net/problems/pair-sum?language=py>

If you need additional support taking these DSA skills and actually applying them, take [**Alvin's**](https://www.linkedin.com/in/alvin-zablan-b73a92117/) *complete* data structures and algorithms course on [**Structy**](https://structy.net/?utm_source=taro). You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

Use [**this link to get 20% off**](https://structy.net/purchase?promo_code=taro20) the entire Structy DSA learning experience.

Follow Alvin on LinkedIn: <https://www.linkedin.com/in/alvin-zablan-b73a92117/>

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