Introduction

In this blog post, we will explore how to solve the LeetCode problem "3273" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

You are given an integer power and two integer arrays damage and health, both having length n. Bob has n enemies, where enemy i will deal Bob damage[i] points of damage per second while they are alive (i.e. health[i] > 0). Every second, after the enemies deal damage to Bob, he chooses one of the enemies that is still alive and deals power points of damage to them. Determine the minimum total amount of damage points that will be dealt to Bob before all n enemies are dead. Example 1: Input: power = 4, damage = [1,2,3,4], health = [4,5,6,8] Output: 39 Explanation: Attack enemy 3 in the first two seconds, after which enemy 3 will go down, the number of damage points dealt to Bob is 10 + 10 = 20 points. Attack enemy 2 in the next two seconds, after which enemy 2 will go down, the number of damage points dealt to Bob is 6 + 6 = 12 points. Attack enemy 0 in the next second, after which enemy 0 will go down, the number of damage points dealt to Bob is 3 points. Attack enemy 1 in the next two seconds, after which enemy 1 will go down, the number of damage points dealt to Bob is 2 + 2 = 4 points. Example 2: Input: power = 1, damage = [1,1,1,1], health = [1,2,3,4] Output: 20 Explanation: Attack enemy 0 in the first second, after which enemy 0 will go down, the number of damage points dealt to Bob is 4 points. Attack enemy 1 in the next two seconds, after which enemy 1 will go down, the number of damage points dealt to Bob is 3 + 3 = 6 points. Attack enemy 2 in the next three seconds, after which enemy 2 will go down, the number of damage points dealt to Bob is 2 + 2 + 2 = 6 points. Attack enemy 3 in the next four seconds, after which enemy 3 will go down, the number of damage points dealt to Bob is 1 + 1 + 1 + 1 = 4 points. Example 3: Input: power = 8, damage = [40], health = [59] Output: 320 Constraints: 1 <= power <= 104 1 <= n == damage.length == health.length <= 105 1 <= damage[i], health[i] <= 104

Explanation

Here's the solution:

• Optimal Attack Order: The key is to attack enemies in decreasing order of their damage output. This minimizes the overall damage received by Bob.
• Calculate Time to Kill: For each enemy, determine the number of seconds it will take to kill them (health / power, rounded up).

• Accumulate Damage: Iterate through the enemies in the sorted order, and for each enemy, calculate the damage Bob receives while killing that enemy.

• Runtime Complexity: O(n log n) due to sorting. Storage Complexity: O(n) due to sorting.

Code

    def min_damage(power: int, damage: list[int], health: list[int]) -> int:
    """
    Calculates the minimum total damage Bob will take before all enemies are dead.

    Args:
        power: The amount of damage Bob deals per second.
        damage: A list of integers representing the damage each enemy deals per second.
        health: A list of integers representing the health of each enemy.

    Returns:
        The minimum total damage Bob will take.
    """
    n = len(damage)
    enemies = []
    for i in range(n):
        enemies.append((damage[i], health[i]))

    # Sort enemies in descending order of damage
    enemies.sort(key=lambda x: x[0], reverse=True)

    total_damage = 0
    alive_damage = sum(d for d, h in zip(damage, health))

    for enemy_damage, enemy_health in enemies:
        time_to_kill = (enemy_health + power - 1) // power  # Ceiling division
        total_damage += alive_damage * time_to_kill
        alive_damage -= enemy_damage

    return total_damage