From 2239760ce21e964181a343489a996076cc13b938 Mon Sep 17 00:00:00 2001
From: Max Nuding <max.nuding@icloud.com>
Date: Wed, 15 Dec 2021 14:20:33 +0100
Subject: [PATCH] 15b

---
 Sources/15/15.swift | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/Sources/15/15.swift b/Sources/15/15.swift
index 9b90183..e06d373 100644
--- a/Sources/15/15.swift
+++ b/Sources/15/15.swift
@@ -29,7 +29,6 @@ struct Coord: Hashable, CustomStringConvertible {
 
 class Day15: Runnable {
     let inputPath: String
-    var field = [Coord]()
     var lastRow: Int = 0
     var lastCol: Int = 0
     var parts = [[ThreatLevel]]()
@@ -71,22 +70,29 @@ class Day15: Runnable {
         lastRow = parts.count - 1
         lastCol = (parts.first?.count ?? 0) - 1
         
-        var unvisited = Set<Coord>()
         // Distances to startNode
         var totalThreatLevel = [Coord: ThreatLevel]()
-        for row in parts.enumerated() {
-            for col in row.element.indices {
-                let c = Coord(row: row.offset, col: col)
-                unvisited.insert(c)
-                //totalThreatLevel[c] = Int.max
+        
+        var unvisited = Set(parts.enumerated().flatMap {row in
+            row.element.indices.map { col in
+                Coord(row: row.offset, col: col)
             }
-        }
+        })
+        var threatLevelDistrubution = [ThreatLevel: Set<Coord>]()
         let startNode = Coord(row: 0, col: 0)
         totalThreatLevel[startNode] = 0
+        threatLevelDistrubution[Int.max] = unvisited
+        threatLevelDistrubution[Int.max]!.remove(startNode)
+        threatLevelDistrubution[0] = Set([startNode])
         
-        while let currentNode = unvisited.min(by: { totalThreatLevel[$0, default: Int.max] < totalThreatLevel[$1, default: Int.max] }) {
-            //var currentNode = !
+        while let threatLevel = threatLevelDistrubution.keys.min() {
+            let currentNode = threatLevelDistrubution[threatLevel]!.first!
             unvisited.remove(currentNode)
+            threatLevelDistrubution[threatLevel]!.remove(currentNode)
+            if threatLevelDistrubution[threatLevel]!.isEmpty {
+                threatLevelDistrubution.removeValue(forKey: threatLevel)
+            }
+            
             if neighbors[currentNode] == nil {
                 neighbors[currentNode] = currentNode
                     .neighbors()
@@ -103,8 +109,14 @@ class Day15: Runnable {
             let currentThreatLevel = totalThreatLevel[currentNode, default: Int.max]
             for a in adjacent {
                 let testCost = parts[a] + currentThreatLevel
-                if totalThreatLevel[a, default: Int.max] > testCost {
+                let currentCost = totalThreatLevel[a, default: Int.max]
+                if currentCost > testCost {
                     totalThreatLevel[a] = testCost
+                    threatLevelDistrubution[currentCost]!.remove(a)
+                    threatLevelDistrubution[testCost, default: Set<Coord>()].insert(a)
+                    if threatLevelDistrubution[currentCost]!.isEmpty {
+                        threatLevelDistrubution.removeValue(forKey: currentCost)
+                    }
                 }
             }
         }