2023 day 05

2023/05/part2/main.go

@@ -0,0 +1,108 @@
+
+package main
+
+import (
+	"bufio"
+	"os"
+	"strings"
+	"strconv"
+)
+
+func main() {
+	reader := bufio.NewReader(os.Stdin);
+
+	text, _ := reader.ReadString('\n')
+	seeds := strings.Split(strings.Trim(strings.Split(text, ": ")[1], "\n"), " ");
+
+	reader.ReadString('\n')
+	mappers := [][]resMap{};
+
+	points := []int{};
+
+	for {
+
+		line, _ := reader.ReadString('\n')
+		if len(line) < 1 {
+			break;
+		}
+
+		mapper := []resMap{};
+
+		for {
+			nextLine, _ := reader.ReadString('\n');
+			seedToSoil := strings.Split(strings.Trim(nextLine, "\n"), " ");
+			if len(seedToSoil) != 3 {
+				break;
+			}
+			destStart, _ := strconv.Atoi(seedToSoil[0]);
+			srcStart, _ := strconv.Atoi(seedToSoil[1]);
+			length, _ := strconv.Atoi(seedToSoil[2]);
+			mapper = append(mapper, resMap{destStart,srcStart,length})
+			points = append(points, seedLocOrigin(mappers, srcStart));
+		}
+
+		mappers = append(mappers, mapper)
+	}
+	
+	min := 0;
+
+	for i := 0; i < len(seeds) -1; i += 2 {
+		start, _ := strconv.Atoi(seeds[i]);
+		length, _ := strconv.Atoi(seeds[i+1]);
+		o := seedLoc(mappers, start);
+		if min == 0 || o < min {
+			min = o;
+		}
+		for _, point := range points {
+			if point > start && point < start + length {
+
+				o := seedLoc(mappers, point);
+				if min == 0 || o < min {
+					min = o;
+				}
+			}
+		}
+	}
+
+	println(min)
+}
+
+func seedLoc(mappers [][]resMap, source int) int {
+	for _, m := range mappers {
+		source = mapSeed(m, source)
+	}
+	return source
+}
+
+func mapSeed(soil []resMap, source int) (int) {
+	for _, m := range soil {
+		if source >= m.srcStart && source < m.srcStart + m.length {
+			return m.destStart + (source - m.srcStart)
+		}
+	}
+	return source
+}
+
+func unMapSeed(soil []resMap, source int) (int) {
+	for _, m := range soil {
+		if source >= m.destStart && source < m.destStart + m.length {
+			return m.srcStart + (source - m.destStart)
+		}
+	}
+	return source
+}
+
+func seedLocOrigin(mappers [][]resMap, source int) int {
+	for i := range mappers {
+		fMaps := mappers[len(mappers)-i-1]
+		source = unMapSeed(fMaps, source)
+	}
+	return source
+}
+
+type resMap struct {
+	destStart int
+	srcStart int
+	length int
+}
+