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Data Structures Easy to Advanced Course
In this lesson, we will lay the foundation for core concepts needed throughout these data structures and al
gorithms
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Data Structures
A data structure organizes data for efficient use and is essential for creating powerful algorithms
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To understand the performanc
e that data structures provide, we need to look at the wild world of computational complexity
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Ho
wever, it does not provide the details surrounding how those methods are implemented
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Almost any mathematical expression containing n can be wrapped around a Big O
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Constant Time Algorithms
Both of the following algorithms run in constant time relative to the input size because they are independe
nt of n
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Algorithm 1
Algorithm 2
Binary Search Algorithm
A classic algorithm for binary search has a logarithmic time complexity
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Then, it selects a midpoint between the
two pointers and checks if the value being searched for is found at the midpoint
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This is the first part of a two-part video series on arrays
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What is a Static Array?
A static array is a fixed-length container containing elements
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Searching Can Take up to the Linear Time Because We Potentially Have to Traverse all the Elements in t
he Array in the Worst Case
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The Static Array is a Fixed Size Con
tainer, so It Cannot Grow Larger or Smaller
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If We Look at a, You Can
See That it Contains the Values 4412, -517, 6039, and 100
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How
ever, This is Not at All a Requirement of the Array
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This Confuses a Lot of Intro Computer Science Students
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This is Part Two of Two in the Array Series
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The size of the array must be greater than or equal to zer
o
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We also include suppress warnings and unchecked due
to issues with generics
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This is part one of two where we will be d
iscussing singly and doubly linked lists
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The last node in a linked list always has a null reference to the next node
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Doubly linked lists contain pointers that point to both the previous and next nodes
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Singly linked lists use less memory than doubly linked lists
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The concept is the same, but it’s trickier due to all the pointers flying
around
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Traverse the list using traverser1
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When you reach the node you wish to remove (in this case, one with a value of 9), set traverser2
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next, effectively removing the node from the list
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Singly linked lists do not have a pointer to the tail
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The size and empty methods are quite intuitive; they retrieve the size of our linked list and determine whet
her it is empty
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The remove method is generic
and removes an arbitrary node
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If the node being removed is at either the head or t
he tail, we detect this and call our methods removeFirst or removeLast
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A stack is a one ended linear data structure that models the real world stack, with two primary operations:
push and pop
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Lastly, we’ll provide some source code for how a stack is implemented using a linked list
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This behavior is common in programming
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It’s rather r
emarkable that we use stacks all the time in programming and never even notice it
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Let’s analyze some examples below to understand w
hat type of bracket sequences are valid and which ones are invalid
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{[]()}
{{[()]}}

{[}()]
{[()}}
We can conclude that the first two bracket sequences are indeed valid, while the last two bracket sequenc
es are invalid
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If our bracket is a left bracket, we push it onto the stack
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If it is empty, then we have an invalid bracket sequence, otherwise we continue popp
ing
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