Question

2) Write an algorithm for a function called list_search which takes 2 parameters: a sequence of elements and a value to search for. The function should search the sequence for the value and return all indicies of instances of the value in the list.

Answer 1

Function list_search()

Problem: Find all the indices of a given value in the given sequence of elements.

Inputs:
1. A sequence of elements, S
2. Value to search, V

Output:
1. A list of indices of all the instance of the value in list

Step 1: Start
Step 2: Initialize a list, LI, to store the list of indices
Step 3: Initialize an integer, I = 0, for counting the index
Step 4: For each element x in S
           4.1:   if x is equal to V, append I into LI
           4.2:   Increment I by 1
Step 5: Return LI
Step 6: Stop

The algorithm translated to python code:
def list_search(S,V):
   LI = []
   I = 0
   for x in S:
       if(x == V):
           LI.append(I)
       I = I + 1
   return LI

#Testing the program
print(list_search([1,4,3,4,5,6],4))

Output:

[1,3]

Note:
Time Complexity of the program: O(n)
because to find the indices of the given value in the list, the value should be compared with all the elements in the given input. Hence, the for loop will run for n times, where n is the number of elements in the list.