Lina’s Training Challenge

Problem Description

Lina is training for a marathon.
Each exercise has an energy cost (in calories), but the more exercises she completes,
the more tired she becomes.

If Lina has already completed j exercises and performs one with e calories,
she will burn:

e × (j + 1)

calories.

Lina can perform the exercises in any order.
Your task is to find the minimum total energy she will use.

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Example

Suppose the energy costs are:

[4, 2, 7]

If Lina performs them in this order (2, 4, 7):

Order	Energy	Total energy used (e × (j + 1))	Cumulative total
1	2	2 × 1 = 2	2
2	4	4 × 2 = 8	10
3	7	7 × 3 = 21	31

✅ Minimum total energy = 31

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Function Description

Write the function:

def linasTraining(energy: list[int]) -> int:

The function should:

• Take a list of energy values.

• Return the minimum total energy Lina needs to spend.

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Sample Input 1

[4, 2, 7]

Sample Output 1

31

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Sample Input 2

[3, 5, 1, 6]

Sample Output 2

41

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Guided Steps

1. Understand the formula.
   For each exercise i (in the chosen order), the energy used is energy[i] × (j + 1),
   where j is the number of exercises already done.

2. Write pseudocode.

   • Think about how the order affects the result.

   • To minimize the total, should Lina do the heaviest or lightest exercises first?

   • Keep a variable to accumulate the total energy.

3. Implement and test.
   Write the Python code, then check that your program matches the sample outputs.