def cumSum(a): s = 0 cum_list = [] for i in a: s = s + i cum_list.append(s) return cum_list l = eval(input('Enter list items in Square bracket:')) print(cumSum(l)) Output: Enter list items in Square bracket: [1, 2, 3, 4] [1, 3, 6, 10] Explanation Function Definition (def cumSum(a):): This line defines a function named cumSum that takes one parameter, a, which is expected to be a list of numbers. Initialize Variables (s=0 and cum_list=[]): s is initialized to 0. This variable will be used to keep track of the cumulative sum. cum_list is initialized as an empty list. This list will store the cumulative sums at each step. Loop Through Each Element (for i in a:): The for loop iterates over each element i in the input list a. Update Cumulative Sum (s = s + i): For each element i, the value of i is added to s, updating the cumulative sum. Append to Cumulative List (cum_list.append(s)): The updated value of s is appended to the cum_list. Return Cumulative List (return cum_list): After the loop completes, the function returns the cum_list containing the cumulative sums. Example Let's go through an example. If the input list is [1, 2, 3, 4], the function will perform the following steps: Initialize s to 0 and cum_list to an empty list. Iteration 1: i = 1, update s to 0 + 1 = 1, append 1 to cum_list -> cum_list = [1]. Iteration 2: i = 2, update s to 1 + 2 = 3, append 3 to cum_list -> cum_list = [1, 3]. Iteration 3: i = 3, update s to 3 + 3 = 6, append 6 to cum_list -> cum_list = [1, 3, 6]. Iteration 4: i = 4, update s to 6 + 4 = 10, append 10 to cum_list -> cum_list = [1, 3, 6, 10]. So, the output for the input list [1, 2, 3, 4] would be [1, 3, 6, 10].
