d10

day10/d10p1.swift

@@ -0,0 +1,49 @@
+import Foundation
+
+struct Coord : Hashable, CustomStringConvertible {
+    let x: Int
+    let y: Int
+    var description: String { return "(\(x), \(y))" }
+    func neighbors() -> [Coord] {
+        return [
+            Coord(x: x-1, y: y), Coord(x: x+1, y: y),
+            Coord(x: x, y: y-1), Coord(x: x, y: y+1)
+        ]
+    }
+    func valid(xLimit: Int, yLimit: Int) -> Bool {
+        return x >= 0 && y >= 0 && x < xLimit && y < yLimit
+    }
+}
+
+func readInput(_ filePath: String) throws -> ([Int:Set<Coord>], Int, Int) {
+    let content = try String(contentsOfFile: filePath, encoding: .ascii)
+    let lines = content.split(separator: "\n").map(Array.init)
+    let map = lines.map { $0.map(String.init).map { Int($0)! } }
+    var topo: [Int:Set<Coord>] = [:]
+    map.enumerated().forEach { i, row in
+        row.enumerated().forEach { j, h in
+            topo[h] = (topo[h] ?? []).union([Coord(x: i, y: j)])
+        }
+    }
+    return (topo, lines.count, lines[0].count)
+}
+
+let (topo, height, width) = try readInput(CommandLine.arguments[1])
+var answer: Int = 0
+//topo.forEach { k, v in print("\(k): \(v)") }
+
+for start in topo[0]! {
+    var froms: Set<Coord> = [start]
+    for altitude in 1...9 {
+        var tos: Set<Coord> = []
+        for from in froms {
+            from.neighbors()
+                .filter { c in c.valid(xLimit: height, yLimit: width) }
+                .filter { c in topo[altitude]!.contains(c) }
+                .forEach { c in tos.insert(c) }
+        }
+        froms = tos
+    }
+    answer += froms.count
+}
+print(answer)

day10/d10p2.swift

@@ -0,0 +1,46 @@
+import Foundation
+
+struct Coord : Hashable, CustomStringConvertible {
+    let x: Int
+    let y: Int
+    var description: String { return "(\(x), \(y))" }
+    func neighbors() -> [Coord] {
+        return [
+            Coord(x: x-1, y: y), Coord(x: x+1, y: y),
+            Coord(x: x, y: y-1), Coord(x: x, y: y+1)
+        ]
+    }
+}
+
+func readInput(_ filePath: String) throws -> ([Int:Set<Coord>], Int, Int) {
+    let content = try String(contentsOfFile: filePath, encoding: .ascii)
+    let lines = content.split(separator: "\n").map(Array.init)
+    let map = lines.map { $0.map(String.init).map { Int($0)! } }
+    var topo: [Int:Set<Coord>] = [:]
+    map.enumerated().forEach { i, row in
+        row.enumerated().forEach { j, h in
+            topo[h] = (topo[h] ?? []).union([Coord(x: i, y: j)])
+        }
+    }
+    return (topo, lines.count, lines[0].count)
+}
+
+let (topo, height, width) = try readInput(CommandLine.arguments[1])
+topo.forEach { k, v in print("\(k): \(v)") }
+
+var currentLayer: [Coord:Int] = Dictionary(
+    uniqueKeysWithValues: topo[0]!.map { coord in (coord, 1) }
+)
+print("\n0: \(currentLayer)")
+for alt in 1...9 {
+    var nextLayer: [Coord:Int] = [:]
+    for (from, score) in currentLayer {
+        from.neighbors()
+            .filter { c in c.x >= 0 && c.y >= 0 && c.x < height && c.y < width }
+            .filter { c in topo[alt]!.contains(c) }
+            .forEach { c in nextLayer[c] = (nextLayer[c] ?? 0) + score }
+    }
+    currentLayer = nextLayer
+    print("\(alt): \(currentLayer)")
+}
+print(currentLayer.values.reduce(0) { s, score in s + score })

day10/input.txt

@@ -0,0 +1,52 @@
+0145677654325490845691012345621876560340100123012398
+1238988998216781932782121234010983401259230034563387
+4323589867205432801543210945125672378768341459654456
+1014678454102301765456901876034561769897652368776301
+6765521543201512350307872962120120850785677879789210
+0896430439810487461217965871298438941454980968654321
+1765012126723596543478014560167569032363211457256762
+2872121035434654302569123441455678121071102340145895
+3961230345985783211098710332334599432980098743232434
+4550145456676890100167000146721087641001217650141325
+9649056765489910651254121035890014550732309654210016
+8738769894676328762343236124301123669845498763227807
+7129787923565439651456347833210008778996787120156998
+1013496014567010340987656944782119211087898031343210
+1012345002198321232876501855693024302332196541034101
+1234567123023450901965432761054435678445087670123256
+0144898454910767845670301622169546589556764581214347
+4343732367867893034981243213678696765698873294309838
+1234351078754702121893214504589787894780987101456789
+0943765469843213210721303698921009683211074560167678
+7856874348765434785630410787652118701202983076298987
+6765989219210125698540521236543025654343892189347567
+5667867804321087582101638347432134509856782345456498
+1054876965691296443492789858901213212790101276012387
+2123965476780125356783498767654300103685230983401456
+3278954587821034219870567658967876234576541092560845
+2567543296930761006721498743478965987655612451076921
+1056230145945852345012345412661234554567803367987830
+2340167034876945123211296401780109693069954298756101
+7887658123985231034500787345691218782178769110343232
+6992349032100112985011216217885011071078978021232349
+5801239844301101676720105606976522362567987876541458
+4321023765432432369838234745983439453454376965430167
+3087610321396565458949549836112378321043105302301298
+2198565410187076327658678921001065439652234211017657
+3233478903216189014547664567632104508701230322928943
+4542369894103273223014523498549812012349821498834012
+7651423765764784132123210210038763676256734567765423
+8960314349845695041012396342121054985109875498656701
+4871005256736786780169487653434873014018766787567892
+5654196149821677893278565694565963223321051096450943
+6743287032120563034567684787696954101438142345321056
+7899180129061432125675893256787845698589233239885469
+3458098938778743210986710143876034787670132178596378
+2167347845609654331235430782932128236101056017687267
+6056256741012103220543521691047659145692347012570167
+7890165432343210110652434598798578036785498743456898
+6784567876758701328701223123623457629876901234347107
+5413218965869232499899810034510256510267892301298256
+4303409954978149581234745218760105100126765410789340
+3212567823019058670365634309451234981237898323870121
+4321016012108767621256565678321015676546767654965432

day10/test.txt

@@ -0,0 +1,8 @@
+89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732

day10/test0.txt

@@ -0,0 +1,4 @@
+0123
+1234
+8765
+9876