Python Coding challenge - Day 527| What is the output of the following Python Code?

 

Code Explanation:

1. Function Definition

\def can_partition(nums):

Defines a function called can_partition that takes a list of integers nums.

Goal: Determine if the list can be split into two subsets with equal sum.

2. Calculate Total Sum

    s = sum(nums)

s stores the total sum of all elements in the list.

3. Check for Odd Total Sum

    if s % 2: return False

If the total sum s is odd, it's impossible to split the list into two equal-sum subsets.

So the function immediately returns False in that case.

4. Initialize Target and Set

    dp, target = {0}, s // 2

target: The sum each subset must have, which is s // 2.

dp: A set that keeps track of all possible subset sums that can be formed using elements seen so far.

Starts with {0} because you can always make a subset sum of 0 (empty subset).

5. Iterate Through Numbers

    for num in nums:

        dp |= {x + num for x in dp}

For each number in nums:

Compute {x + num for x in dp} → all new subset sums formed by adding num to existing subset sums.

dp |= ... means we add all new subset sums to dp.

This builds up all possible subset sums that can be formed from the elements in nums.

6. Check for Target Sum

    return target in dp

After processing all numbers, check if target is in dp.

If yes → There exists a subset whose sum is exactly target, and thus the rest must also sum to target → return True.

Otherwise → return False.

7. Function Call and Output

print(can_partition([1, 5, 11, 5]))

Input list: [1, 5, 11, 5]

Total sum = 22, so target = 11.

One possible partition: [11] and [1, 5, 5], both sum to 11.

Output: True

Final Output:

True