Maximum Product Difference: NLogN

-

Problem can be solved in NLogN with 2 lines: sort and take the extremes. That's it. Problem and code are below, cheers, ACC.

Maximum Product Difference Between Two Pairs - LeetCode

1913. Maximum Product Difference Between Two Pairs
Easy

The product difference between two pairs (a, b) and (c, d) is defined as (a * b) - (c * d).

  • For example, the product difference between (5, 6) and (2, 7) is (5 * 6) - (2 * 7) = 16.

Given an integer array nums, choose four distinct indices w, x, y, and z such that the product difference between pairs (nums[w], nums[x]) and (nums[y], nums[z]) is maximized.

Return the maximum such product difference.

 

Example 1:

Input: nums = [5,6,2,7,4]
Output: 34
Explanation: We can choose indices 1 and 3 for the first pair (6, 7) and indices 2 and 4 for the second pair (2, 4).
The product difference is (6 * 7) - (2 * 4) = 34.

Example 2:

Input: nums = [4,2,5,9,7,4,8]
Output: 64
Explanation: We can choose indices 3 and 6 for the first pair (9, 8) and indices 1 and 5 for the second pair (2, 4).
The product difference is (9 * 8) - (2 * 4) = 64.

 

Constraints:

  • 4 <= nums.length <= 104
  • 1 <= nums[i] <= 104

public int MaxProductDifference(int[] nums)
{
    Array.Sort(nums);
    return nums[nums.Length - 1] * nums[nums.Length - 2] - nums[0] * nums[1];
}

Comments

Post a Comment

Popular posts from this blog

Advent of Code - Day 6, 2024: BFS and FSM

-
Image
To solve this Advent of Code (parts 1 and 2), I used Breadth-First Search (BFS) to keep moving the guard as well as Finite State Machine (FSM) to control the directions. This solves part 1 easily. Part 2 can be solved using the same technique, takes a little longer since you need to try every empty cell, but it eventually does the trick (takes a min or so). Code is down below, cheers, ACC. Day 6 - Advent of Code 2024 using System.IO; using System.Collections; using System; using System.Text; using System.Text.RegularExpressions; using System.ComponentModel.DataAnnotations; Process2(); void Process() { string fileName = "input.txt"; FileInfo fileInfo = new FileInfo(fileName); StreamReader sr = fileInfo.OpenText(); List map = new List (); int startRow = 0; int startCol = 0; while (!sr.EndOfStream) { string line = sr.ReadLine().Trim(); map.Add(new StringBuilder(line)); int indexStart = line.IndexOf('^'); ...
Read more

Golang vs. C#: performance characteristics (simple case study)

-
Image
This is an interesting example to study the performance characteristics of Golang compared to C# for a very particular case (not generalized though).  The same code was written in C# and Golang (literally translated from one to the other). Below you'll be able to see the source code for both. The problem is a simple post-order DFS in a tree-like graph. The code in C# times out (TLE = Time Limited Exceeded). The code in Golang not only works but beats 100% of the other Golang submissions. Take a look the image below: Some potential reasons for the performance gains from Go in this particular example are: 1. Language and Runtime Differences:    Go is compiled directly to machine code, while C# typically runs on a virtual machine (CLR).    Go has a simpler runtime with less overhead compared to the .NET runtime.    Go's garbage collector is designed for low latency, which can lead to better performance in some scenarios. 2. Data Structures:    G...
Read more

Advent of Code - Day 7, 2024: Backtracking and Eval

-
Image
Problem today requires backtracking and eval (evaluating a mathematical expression in the format of a string). Glad that it used a left-2-right evaluation, makes for an easy parsing and not overly complicated evaluation function. Code is down below for parts 1 and 2. Cheers, ACC. Day 7 - Advent of Code 2024 using System.IO; using System.Collections; using System; using System.Text; using System.Text.RegularExpressions; using System.ComponentModel.DataAnnotations; Process2(); void Process() { string fileName = "input.txt"; long retVal = 0; FileInfo fileInfo = new FileInfo(fileName); StreamReader sr = fileInfo.OpenText(); while (!sr.EndOfStream) { string line = sr.ReadLine().Trim(); string[] parts1 = line.Split(':'); long target = Int64.Parse(parts1[0]); string[] numbers = parts1[1].Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries); if (TryAll1(numbers, target, "", 0)) r...
Read more