LeetCode in Net

502. IPO

Hard

Suppose LeetCode will start its IPO soon. In order to sell a good price of its shares to Venture Capital, LeetCode would like to work on some projects to increase its capital before the IPO. Since it has limited resources, it can only finish at most k distinct projects before the IPO. Help LeetCode design the best way to maximize its total capital after finishing at most k distinct projects.

You are given n projects where the ith project has a pure profit profits[i] and a minimum capital of capital[i] is needed to start it.

Initially, you have w capital. When you finish a project, you will obtain its pure profit and the profit will be added to your total capital.

Pick a list of at most k distinct projects from given projects to maximize your final capital, and return the final maximized capital.

The answer is guaranteed to fit in a 32-bit signed integer.

Example 1:

Input: k = 2, w = 0, profits = [1,2,3], capital = [0,1,1]

Output: 4

Explanation:

Since your initial capital is 0, you can only start the project indexed 0.

After finishing it you will obtain profit 1 and your capital becomes 1.

With capital 1, you can either start the project indexed 1 or the project indexed 2.

Since you can choose at most 2 projects, you need to finish the project indexed 2 to get the maximum capital.

Therefore, output the final maximized capital, which is 0 + 1 + 3 = 4.

Example 2:

Input: k = 3, w = 0, profits = [1,2,3], capital = [0,1,2]

Output: 6

Constraints:

• 1 <= k <= 105
• 0 <= w <= 109
• n == profits.length
• n == capital.length
• 1 <= n <= 105
• 0 <= profits[i] <= 104
• 0 <= capital[i] <= 109

Solution

using System;
using System.Collections.Generic;

public class Solution {
    public int FindMaximizedCapital(int k, int w, int[] profits, int[] capital) {
        // Min-heap for projects based on capital required
        // TElement is int[] {profit, capital}, TPriority is capital (for min-heap)
        // The comparer here compares the TPriority values (which are 'int').
        var minCapital = new PriorityQueue<int[], int>(); // Default comparer for int is min-heap
        // Max-heap for projects based on profit
        // TElement is int[] {profit, capital}, TPriority is profit (for max-heap)
        // We need a custom comparer for TPriority 'int' to make it a max-heap.
        // Compares priority values (profits)
        var maxProfit = new PriorityQueue<int[], int>(Comparer<int>.Create((p1, p2) => p2.CompareTo(p1)));
        for (int i = 0; i < profits.Length; i++) {
            if (w >= capital[i]) {
                // Enqueue the project (int[]) with its profit as priority for the max-heap
                maxProfit.Enqueue(new int[] { profits[i], capital[i] }, profits[i]);
            } else {
                // Enqueue the project (int[]) with its capital as priority for the min-heap
                minCapital.Enqueue(new int[] { profits[i], capital[i] }, capital[i]);
            }
        }
        int count = 0;
        while (count < k && maxProfit.Count > 0) {
            // Dequeue returns the element (int[]), not the priority
            int[] temp = maxProfit.Dequeue();
            w += temp[0]; // Add profit to current capital
            count++;
            // Move projects from minCapital to maxProfit if current capital (w) is sufficient
            // Peek() returns the element (int[]), not the priority.
            while (minCapital.Count > 0 && minCapital.Peek()[1] <= w) {
                int[] project = minCapital.Dequeue();
                // Enqueue the moved project with its profit as priority into maxProfit heap
                maxProfit.Enqueue(project, project[0]);
            }
        }
        return w;
    }
}

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