IB Recipe Book

This page contains the IB way to code common operations found in Paper 1 (Pre 2026)

Array vs Python List

1. Data Type Flexibility

• Array: Typically, arrays are homogeneous, meaning all elements must be of the same data type (e.g., all integers or all floats).

• Python List: Lists in Python are heterogeneous, allowing you to store elements of different types (e.g., integers, strings, objects) in the same list.

2. Size and Resizing

• Array: The size of an array is fixed upon creation. You cannot change its size without creating a new array.

• Python List: Lists are dynamic; you can easily add or remove elements, and the list will resize automatically.

3. Memory Management

• Array: Arrays are more memory-efficient for large datasets since they store elements in contiguous memory locations.

• Python List: Lists may use more memory due to their flexibility and the overhead of storing type information for each element.

4. Performance

• Array: Generally, arrays can offer better performance for numerical computations due to their fixed size and type.

• Python List: While lists are versatile, they may be slower for certain operations compared to arrays, especially when dealing with large datasets.

5. Built-in Functions

• Array: In languages like C, you have to implement many operations manually (like sorting or searching).

• Python List: Python provides a rich set of built-in methods for lists (like .append(), .remove(), and .sort()) that make manipulation straightforward.

Things to avoid

1. List Slicing

2. Do not use any list methods

3. Do not use map(); filter(); enumerate(); max(); min(); set(); reversed()

4. Use of set, tuple, or dictionary data types

Creating an Array during IB Exam

size = int(input()) # Set size of the array
array = [None for _ in range(0, size)]

for i in range(0, size):
    array[i] = input()

This code mimics the creation fixed size arrays.

Explanation

• Variable size is inputted to limit the size of the array

• Variable array is initialized using list comprehension to create a list in python with size many empty spaces for future inputted value

  • Empty spaces are using the None keyword for empty values

• the for loop iterates size many times to input values at index i

  • If inputting numeric values please type cast the input() function in the for loop

Find the maximum/minimum value in an array

This is assuming we can't use max() nor min()

# let array represent an array of values
n = len(array) # Set n to length of given array

# Initialize variables to hold the first value
smallest = array[0]
largest = array[0]

# Logic: compare against the variable above, and update if necessary
for i in range(1, n):
    if array[i] < smallest:
        smallest = array[i]
    
    if array[i] > largest:
        largest = array[i]

# If you only need either max or min, you can remove the unneeded if statement
# This can also be put into a function/sub-program if needed

Find the maximum/minimum value's index in an array

This is where we find the index value of our max and min values

# let array represent an array of values
n = len(array) # Set n to length of given array

# Initialize variables to hold the first value
smallest = array[0]
largest = array[0]

smallest_location = 0 # smallest index holder
largest_location = 0 # largest index holder

# Logic: compare against the variable above, and update if necessary
for i in range(1, n):
    if array[i] < smallest:
        smallest = array[i]
        smallest_location = i
    
    if array[i] > largest:
        largest = array[i]
        largeest_location = i

Calculate the average from an array of values

# let array represent an array of values
n = len(array) # Set n to length of given array

total_sum = 0 # initialize total_sum variable

for i in range(0, n):
    total_sum = total_sum + array[i]

average = total_sum / n

Linear search an array to find a target value

def linear_search(array, target):
    # let array represent an array of values
    # let target the value we search for
    n = len(array) # Set n to length of given array
    
    for i in range(0, n):
        if array[i] == target:
            return i
    # end of for
    return -1 # let -1 be an error code for not found
# end of linear search

Binary search an array to find a target value

def binary_search(array, target):
    # let array represent an array of values that are sorted
    # let target the value we search for
    n = len(array) # Set n to length of given array
    left = 0
    right = n - 1
    
    while left <= right:
        mid = (left + right) // 2 # specify that // means a floor division
        if array[mid] < target:
            left = mid + 1
        elif array[mid] > target:
            right = mid - 1
        else:
            return mid
    # end of while
    return -1 # let -1 be an error code for not found
# end of linear search

How to sort an array of data using Bubble Sort

# This algorithm sorts in ascending order
# let array represent an array of values
n = len(array) # Set n to length of given array
swapped = True # initialized to true to start our algorithm

while swapped == True:
    swapped = False
    for i in range(1, n):
        left = array[i-1]
        right = array[i]
        
        if left > right: # for descending order change > to <
            array[i] = left
            array[i-1] = right
            swapped = True
    # end of inner for
# end of outer while

How to sort connected arrays using bubble sort

# This algorithm sorts in ascending order
# let array represent an array of values
# let array2 represent another array of values

# this behaviour is common for situation where:
#     one array has names
#     the other array has values for the names
#     often called "parallel arrays"
#     they connect values from different arrays by using consistent index values

size = len(array) # Set size to length of given array
size2 = len(array2) # Set size2 to length of other array

swapped = True # initialized to true to start our algorithm

while swapped == True:
    swapped = False
    for i in range(1, n):
        left = array[i-1]
        right = array[i]
        
        if left > right: # for descending order change > to <
            array[i] = left
            array[i-1] = right
            swapped = True
            
            # Since the first array swapped values, swap the other array
            temp = array2[i]
            array2[i] = array2[i-1]
            array2[i-1] = temp
        # end of if
    # end of inner for
# end of outer while

Determine the difference between one array and another

We are trying to output a new array/collection that determines which values in one of the array does not appear in the other

# let array1 represent an array
# let array2 represent another array
# let diff represent an array that holds the non-shared values

a1_size = len(array1)
a2_size = len(array2)

for i in range(0, a1_size):
    found = False
    for j in range(0, a2_size):
        if array1[i] == array2[j]:
            found = True
            break
    # end of inner for
    
    if found == False:
        diff.append(array1[i])
# end of outer for

# We must also do this again except starting from array2
for j in range(0, a2_size):
    found = False
    for i in range(0, a1_size):
        if array1[i] == array2[j]:
            found = True
            break
    # end of inner for
    
    if found == False:
        diff.append(array2[j])

Access individual digits from a number from right to left without String manipulation

# let num be an integer
# our goal is to get the individual digits
#     starting from the "ones" column
#     Example: 1234 outputs 
#       4
#       3
#       2
#       1

while num > = 0:
    current_digit = num % 10
    num = num // 10 # floor division of 10
    print(current_digit)