Problem solving + Pseudocode

Question 1

What is a good first step when solving a new programming problem?

Answer 1

Understand the inputs and desired outputs, then break the problem into smaller steps.

Question 2

What does ‘decomposition’ mean in programming?

Answer 2

Breaking a problem into smaller, more manageable sub-problems.

Question 3

What does ‘divide and conquer’ mean?

Answer 3

A technique where a problem is divided into smaller parts, each solved recursively, and combined.

Question 4

Give an example of divide and conquer.

Answer 4

Merge Sort: divide the array, sort each half, merge them back together.

Question 5

Why is recursion often used in divide and conquer?

Answer 5

Because each subproblem can be solved with the same method, reducing code repetition.

Question 6

How would you write pseudocode to reverse a string?

Answer 6

function reverse(s): result = “”, for i from length(s)-1 to 0: result += s[i], return result

Question 7

How would you find the largest number in an array (pseudocode)?

Answer 7

function max(arr): largest = arr[0], for each item in arr: if item > largest then largest = item, return largest

Question 8

Write pseudocode for a linear search.

Answer 8

function linearSearch(arr, target): for each item in arr: if item == target: return true, return false

Question 9

Write pseudocode for counting how many times a value appears in a list.

Answer 9

function countOccurrences(arr, value): count = 0, for item in arr: if item == value then count += 1, return count

Question 10

Why is it useful to write pseudocode before coding?

Answer 10

It helps plan logic without worrying about syntax, making the code easier to write and debug.

Question 11

How do you trace a recursive function by hand?

Answer 11

Use a call stack: track each function call and return value step by step.

Question 12

What’s the purpose of base cases in recursion?

Answer 12

They stop the recursion to prevent infinite loops and return final results.

Question 13

What are the three parts of a recursive function?

Answer 13

Base case, recursive call, and a step that moves toward the base case.

Question 14

Describe the problem-solving pattern: Input → Process → Output.

Answer 14

It means: Read inputs → Perform operations → Return/display results.

Question 15

Write pseudocode for checking if a number is even.

Answer 15

function isEven(n): return n % 2 == 0

Question 16

What is an algorithm?

Answer 16

A finite set of steps that solve a problem or complete a task.

Question 17

How would you break down the problem ‘Find the average of a list of numbers’?

Answer 17

Add all numbers, divide by the number of items, return result.

Question 18

What is dry-run testing?

Answer 18

Manually walking through code or pseudocode to track variable values and ensure correctness.

Question 19

How can you simplify a complex problem?

Answer 19

Identify repeated patterns, use functions, or split into subproblems.

Question 20

What is an example of a brute-force approach?

Answer 20

Trying all possible combinations, such as checking every pair of numbers for a sum.

Question 21

Write pseudocode to count how many even numbers are in a list.

Answer 21

function countEvens(arr): count = 0, for each num in arr: if num % 2 == 0 then count += 1, return count

Question 22

Write pseudocode to check if a list is sorted in ascending order.

Answer 22

function isSorted(arr): for i from 0 to length(arr)-2: if arr[i] > arr[i+1] then return false, return true

Question 23

Write pseudocode to calculate the sum of all numbers in a list.

Answer 23

function sumList(arr): total = 0, for each num in arr: total += num, return total

Question 24

Write pseudocode to reverse the order of a list.

Answer 24

function reverseList(arr): result = [], for i from length(arr)-1 to 0: result.append(arr[i]), return result

Question 25

Write pseudocode to return the index of the smallest number in a list.

Answer 25

function indexOfMin(arr): minIndex = 0, for i from 1 to length(arr)-1: if arr[i] < arr[minIndex] then minIndex = i, return minIndex

Question 26

Write pseudocode to remove duplicates from a list.

Answer 26

function removeDuplicates(arr): result = [], for each item in arr: if item not in result then result.append(item), return result

Question 27

Write pseudocode to count the frequency of each item in a list.

Answer 27

function countFrequencies(arr): freq = empty dictionary, for each item in arr: if item in freq then freq[item] += 1 else freq[item] = 1, return freq

Question 28

Write pseudocode to return True if two lists are equal (same values, same order).

Answer 28

function areEqual(a, b): if length(a) != length(b) then return false, for i from 0 to length(a)-1: if a[i] != b[i] then return false, return true

Question 29

Write pseudocode to merge two sorted lists into one sorted list.

Answer 29

function mergeSorted(a, b): result = [], i = 0, j = 0, while i < length(a) and j < length(b): if a[i] < b[j] then result.append(a[i]); i += 1 else result.append(b[j]); j += 1, append remaining elements from a and b, return result

Question 30

Write pseudocode to check if a string is a palindrome.

Answer 30

function isPalindrome(s): for i from 0 to length(s)//2: if s[i] != s[length(s)-1-i] then return false, return true