Discussion on: Advent of Code 2019 Solution Megathread - Day 12: The N-Body Problem

[Rizwan]

Quick and dirty part one in swift. Need more time for part 2.

import Cocoa

let input = """
<x=17, y=5, z=1>
<x=-2, y=-8, z=8>
<x=7, y=-6, z=14>
<x=1, y=-10, z=4>
""".components(separatedBy: "\n")

let pattern = "<x=(.+), y=(.+), z=(.+)>"
let regex = try? NSRegularExpression(pattern: pattern, options: [])

var vectors = input.map { line -> [Int] in
    if let match = regex?.firstMatch(in: line, options: [], range: NSRange.init(location: 0, length: line.utf8.count)) {
        if let x = Range(match.range(at: 1), in: line),
            let y = Range(match.range(at: 2), in: line),
            let z = Range(match.range(at: 3), in: line) {
            return [Int(line[x])!, Int(line[y])!, Int(line[z])!]
        }
    }
    return []
}

print(vectors)


func partOne() -> Int {
    var vel: [[Int]] = [[0,0,0],[0,0,0],[0,0,0],[0,0,0]]
    for _ in 0 ... 999 {
        for i in 0 ... vectors.count - 1 {
            for j in 0 ... vectors.count - 1  {
                for k in 0 ... vectors[i].count - 1 {
                    //print("\(i) \(j) \(k)")
                    if vectors[i][k] < vectors[j][k] {
                        vel[i][k] += 1
                    }
                    else if vectors[i][k] > vectors[j][k] {
                        vel[i][k] -= 1
                    }
                }
            }
        }
        for i in 0 ... vectors.count - 1 {
            for k in 0 ... vectors[i].count - 1 {
                vectors[i][k] += vel[i][k]
            }
        }
    }

    var p1 = 0
    for i in 0 ... vectors.count - 1  {
        var pot = 0
        var kin = 0
        for k in 0 ... vectors[i].count - 1 {
            pot += abs(vectors[i][k])
            kin += abs(vel[i][k])
        }
        p1 += pot*kin
    }

    print(vectors)
    print(vel)
    print(p1)
    return p1
}

print(partOne())

[Rizwan]

Forgot to post day 12 part two solution - It Took long time and don't know any leads so I checked the hit from r site and it was easy ride from that.

Swift code can be found here github.com/rizwankce/AdventOfCode/...