added day14 solutions, weighted graph BF traversals

2026-05-18 19:13:27 +02:00 · 2020-08-04 16:15:19 -04:00
parent 9c85f180ad
commit 1b84060b80
3 changed files with 218 additions and 0 deletions
@@ -19,3 +19,4 @@ Day | Name | Type of Algo & Notes
 11 | Space Police | - More Intcode stuff... <br> - __2D Array/Slice manipulation__ and a bit of maths/graphing <br> - Implemented a __RotateGrid__ algo
 12 | The N-Body Problem | I like to call this a _(harmonic) frequency_ algo. Finding the harmonic frequency of multiple bodies/items and then finding the Least Common Multiple of those frequencies will tell you when all the bodies have returned to their initial state. <br> - I've used this approach for a leetcode problem about prisoners in jail cells too
 13 | Care Package | Intcode again! It's basically every other day... <br> - part1: 2D array manipulation again <br> - part2: holy algo, some logic to basically play Bricks game. <br> - This is more of a design question for how you manage state
+14 | Space Stoichiometry | __Weighted Graph and Breadth First Traversals__ <br> - Because not all of the products have a quantity of 1, it complicates the graph's data model. I ended up mapping the product/chemical name to a map of its stoichiometry where the product's number is positive & reactants were negative. <br> - part2: not just a simple division because of "extra byproducts" of generating each piece of fuel. I just let this brute force thing run for ~30 seconds...
@@ -0,0 +1,102 @@
+package main
+
+import (
+	"adventofcode/util"
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	input := util.ReadFile("../input.txt")
+	stoichiometryGraph := makeDependencyGraph(strings.Split(input, "\n"))
+
+	neededChemicals := map[string]int{"FUEL": 1}
+
+	// fmt.Println(stoichiometryGraph, neededChemicals)
+
+	// while the neededChemicals map has positive values for keys besides "ORE"
+	for !isOnlyOres(neededChemicals) {
+		// iterate through neededChemicals
+		for neededChemical, quantityNeeded := range neededChemicals {
+			// if a positive value is found for a neededChemical besides "ORE"
+			if quantityNeeded > 0 && neededChemical != "ORE" {
+				// find its reaction in the stoichiometryGraph
+				reactionStoichiometry := stoichiometryGraph[neededChemical]
+
+				// determine the number of times the reactionStoichiometry must be run
+				timesToRun := quantityNeeded / reactionStoichiometry[neededChemical]
+				if quantityNeeded%reactionStoichiometry[neededChemical] > 0 {
+					timesToRun++
+				}
+
+				// decrement all of the values in neededChemicals map with this reaction's details (* timesToRun)
+				for reactionChemical, chemicalStoich := range reactionStoichiometry {
+					neededChemicals[reactionChemical] -= chemicalStoich * timesToRun
+				}
+			}
+		}
+	}
+
+	// Print final output
+	fmt.Println("ORE needed", neededChemicals["ORE"])
+}
+
+// Creates a graph that maps the products name to its full reaction stoichiometry
+func makeDependencyGraph(reactions []string) map[string]map[string]int {
+	graph := make(map[string]map[string]int)
+
+	for _, reaction := range reactions {
+		product, reactionStoichiometry := parseReaction(reaction)
+		graph[product] = reactionStoichiometry
+	}
+
+	return graph
+}
+
+// parseReaction takes in a line of the input i.e. a reaction in a string
+// parses all its details and returns the generated product as a string
+// and a map of all products to the quantity used/produced by the reaction
+//   for produced chemicals, map value will be > 0, inputs will be < 0
+func parseReaction(reaction string) (string, map[string]int) {
+	reactionStoichiometry := make(map[string]int)
+
+	splitByArrow := strings.Split(reaction, " => ")
+	productStr := splitByArrow[1]
+	reactantsStr := splitByArrow[0]
+
+	// handle product
+	productQty, productName := parseQtyAndName(productStr)
+
+	reactionStoichiometry[productName] = productQty
+
+	// split reactants via comma first
+	reactantsSli := strings.Split(reactantsStr, ", ")
+	for _, str := range reactantsSli {
+		reactantQuantity, reactantName := parseQtyAndName(str)
+		reactionStoichiometry[reactantName] = -1 * reactantQuantity
+	}
+
+	return productName, reactionStoichiometry
+}
+
+// parse an inputted string of the for "<number> <string>" and return the int & string
+func parseQtyAndName(input string) (int, string) {
+	split := strings.Split(input, " ")
+
+	quantity, _ := strconv.Atoi(split[0])
+	name := split[1]
+
+	return quantity, name
+}
+
+// helper function to determine if the neededChemicals graph is "complete"
+// it is complete if there only positive value is for the chemical "ORE"
+func isOnlyOres(neededChemicals map[string]int) bool {
+	for key, val := range neededChemicals {
+		if key != "ORE" && val > 0 {
+			return false
+		}
+	}
+	return true
+}
@@ -0,0 +1,115 @@
+package main
+
+import (
+	"adventofcode/util"
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// const will be comparable to any int type?
+const trillion int = 1000000000000
+
+func main() {
+	input := util.ReadFile("../input.txt")
+	stoichiometryGraph := makeDependencyGraph(strings.Split(input, "\n"))
+
+	// give the brute force algo a big headstart? 1 million fuels to start?
+	var fuelMade int = 1000000
+	neededChemicals := map[string]int{"FUEL": fuelMade}
+
+	// brute force this while the ore count is below 1 trillion
+	for neededChemicals["ORE"] <= trillion {
+		neededChemicals["FUEL"]++
+		// while the neededChemicals map has positive values for keys besides "ORE"
+		for !isOnlyOres(neededChemicals) {
+			// iterate through neededChemicals
+			for neededChemical, quantityNeeded := range neededChemicals {
+				// if a positive value is found for a neededChemical besides "ORE"
+				if quantityNeeded > 0 && neededChemical != "ORE" {
+					// find its reaction in the stoichiometryGraph
+					reactionStoichiometry := stoichiometryGraph[neededChemical]
+
+					// determine the number of times the reactionStoichiometry must be run
+					timesToRun := quantityNeeded / reactionStoichiometry[neededChemical]
+					if quantityNeeded%reactionStoichiometry[neededChemical] > 0 {
+						timesToRun++
+					}
+
+					// decrement all of the values in neededChemicals map with this reaction's details (* timesToRun)
+					for reactionChemical, chemicalStoich := range reactionStoichiometry {
+						neededChemicals[reactionChemical] -= chemicalStoich * timesToRun
+					}
+				}
+			}
+		}
+
+		// if you don't exceed the 1 trillion ORE, increment fuelMade
+		if neededChemicals["ORE"] < trillion {
+			fuelMade++
+		}
+		fmt.Println("Making FUEL... Remaining ORE:", trillion-neededChemicals["ORE"])
+	}
+
+	// Print final output
+	fmt.Println("\nFinal amount of FUEL", fuelMade)
+}
+
+// Creates a graph that maps the products name to its full reaction stoichiometry
+func makeDependencyGraph(reactions []string) map[string]map[string]int {
+	graph := make(map[string]map[string]int)
+
+	for _, reaction := range reactions {
+		product, reactionStoichiometry := parseReaction(reaction)
+		graph[product] = reactionStoichiometry
+	}
+
+	return graph
+}
+
+// parseReaction takes in a line of the input i.e. a reaction in a string
+// parses all its details and returns the generated product as a string
+// and a map of all products to the quantity used/produced by the reaction
+//   for produced chemicals, map value will be > 0, inputs will be < 0
+func parseReaction(reaction string) (string, map[string]int) {
+	reactionStoichiometry := make(map[string]int)
+
+	splitByArrow := strings.Split(reaction, " => ")
+	productStr := splitByArrow[1]
+	reactantsStr := splitByArrow[0]
+
+	// handle product
+	productQty, productName := parseQtyAndName(productStr)
+
+	reactionStoichiometry[productName] = productQty
+
+	// split reactants via comma first
+	reactantsSli := strings.Split(reactantsStr, ", ")
+	for _, str := range reactantsSli {
+		reactantQuantity, reactantName := parseQtyAndName(str)
+		reactionStoichiometry[reactantName] = -1 * reactantQuantity
+	}
+
+	return productName, reactionStoichiometry
+}
+
+// parse an inputted string of the for "<number> <string>" and return the int & string
+func parseQtyAndName(input string) (int, string) {
+	split := strings.Split(input, " ")
+
+	quantity, _ := strconv.Atoi(split[0])
+	name := split[1]
+
+	return quantity, name
+}
+
+// helper function to determine if the neededChemicals graph is "complete"
+// it is complete if there only positive value is for the chemical "ORE"
+func isOnlyOres(neededChemicals map[string]int) bool {
+	for key, val := range neededChemicals {
+		if key != "ORE" && val > 0 {
+			return false
+		}
+	}
+	return true
+}