Week 5 Test

Question 1

what is complexity analysis?

Answer 1

reading code and determining the rate of growth through analysis instead of manually testing the code

Question 2

what is big o notation used for

Answer 2

to express complexity analysis

Question 3

what is Big o’s main concern

Answer 3

the general shape of the growth curve when a function is passed in a large value

Question 4

why is big O not concerned with small values?

Answer 4

computers are so fast that even inefficient code returns almost immediately for a small number

Question 5

what is the correlation between code beginning to behaving slowly and the steep of efficiency curve

Answer 5

the steeper the code, the faster the performance will degrade

Question 6

what does it mean for a function to have constant growth

Answer 6

the runtime remains constant whether the input os large or small

Question 7

what does space complexity describe?

Answer 7

how much memory the function requires

Question 8

what are the space and time complexities of arr.push

Answer 8

time: 1*
space: 1*
requires no shifting and happens in place

Question 9

what are the space and time complexities of arr.pop

Answer 9

Time: 1
space: 1
requires no shifting and happens in place

Question 10

what are the space and time complexities of arr.shift

Answer 10

time: n
space: 1
requires all elements shift to the left by one, but happens in place

Question 11

what are the space and time complexities of arr.unshift

Answer 11

time: n
space: 1
requires all elements shift to the right by one, but happens in place

Question 12

what are the space and time complexities of arr.splice

Answer 12

time: n
space: n*
requires shifting to fill empty spaces and returns an array possibly of unknown length

Question 13

what are the space and time complexities of slice

Answer 13

time: n
space: n
ceates a copy of the old array with some of all elements slice out; the values sliced have to be copied individually

Question 14

what are the space and time complexities of arr.indexOf

Answer 14

time: n
space: 1
this will search and visit each node and the worst case is that the elemt is at the end of the array or not present at all, no space required

Question 15

what are the space and time complexities of arr.map

Answer 15

time: n
space: n
creates a new array with some function applied to each element this is with the assumption that the cb is O(1)

Question 16

what are the space and time complexities of arr.filter

Answer 16

time: n
space: n
iterates over each element and adds values to a new array based on booleans

Question 17

what are the space and time complexities of arr.reduce

Answer 17

time: n
space: 1
iterates over each element and applies a reducer function. assumes reducer is O(1); no additional space required

Question 18

what are the space and time complexities of arr.reverse

Answer 18

time: n
space: 1
moves all n elements in place

Question 19

what are the space and time complexities of spread

Answer 19

time: n
space: n
copy each element into a new array without altering the original

Question 20

what is XOR and what is its symbol

Answer 20

the symbol is ^; XOR means the exclusive or, so one or the other, but not both

Question 21

what does the base refer to in a counting system?

Answer 21

how many digits there are in the system

Question 22

what is the relationship between bits and bytes

Answer 22

bits is short for binary digits which refers to each individual digit in a binary code
a group of 8 bits is a byte

Question 23

what is ASCII

Answer 23

the american standatrd code or information interchange
a standard for changing bits into characters

Question 24

how to go from base 10 to base 2 or base 16

Answer 24

variableHoldingNumber.toString(baseNumberOfTypeGoingTo)

Question 25

how to go from base 16 or base 2 to base 10

Answer 25

parseInt(stringOfOtherNumberType, baseNumberOfTypeComingFrom)

Question 26

how to go from decimal to ASCII

Answer 26

String.fromCharCode(number)
this will accept any tyoe of number not even just decimal

Question 27

how to go from ASCII to decimal

Answer 27

String.protoype.charCodeAt(index)

Question 28

what is memory

Answer 28

refers to random access memory aka RAM which dtores data for programs currently in use including the operating system and background processes

Question 29

what is the difference between RAM and drive storage

Answer 29

drive storage is for long term data storage
RAM is much faster but also more expensive per bit
RAM requires active power source, but drive storage can persit data without power

Question 30

what is a computer science array

Answer 30

a sequence of elements of the same type stored in a contiguous block of memory

Question 31

what is a hash function

Answer 31

a function that takes in an input, runs it through a set of deterministic steps and returns a scrambled output. given the same input, it will always return the same output

Question 32

what is SHA256

Answer 32

a secure hashing algorythm that given any number of bits, will return an output of 256 bits
this will retirn a completely different output for similar inputs