AoC, Day 5, Parts 1 & 2 (Solved)

* Will come back to look at part 2. Extremely slow and inefficient.
* Or maybe I wont lol, YOU'RE NOT THE BOSS OF ME.

2023/05/code.go

@@ -0,0 +1,145 @@
+package main
+
+import (
+	"math"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/jpillora/puzzler/harness/aoc"
+)
+
+func main() {
+	aoc.Harness(run)
+}
+
+// on code change, run will be executed 4 times:
+// 1. with: false (part1), and example input
+// 2. with: true (part2), and example input
+// 3. with: false (part1), and user input
+// 4. with: true (part2), and user input
+// the return value of each run is printed to stdout
+
+func mapRange(ranges [][]int, t int) int {
+	for _, r := range ranges {
+		if t >= r[0] && t <= r[1] {
+			// In range, map
+			diff := t - r[0]
+			return r[2] + diff
+		}
+	}
+	return t
+}
+
+func buildOnRange(ranges [][]int, line string) [][]int {
+	lineSplit := strings.Split(line, " ")
+
+	rangeStart, _ := strconv.Atoi(lineSplit[1])
+	rangeLength, _ := strconv.Atoi(lineSplit[2])
+	mapStart, _ := strconv.Atoi(lineSplit[0])
+
+	return append(ranges, []int{rangeStart, rangeStart + rangeLength - 1, mapStart})
+}
+
+func run(part2 bool, input string) any {
+	// when you're ready to do part 2, remove this "not implemented" block
+	if part2 {
+		lines := strings.Split(input, "\n")
+
+		seedPairs := regexp.MustCompile(`\d+ \d+`).FindAllString(lines[0], -1)[1:]
+		seeds := make([][]int, 0)
+		for _, s := range seedPairs {
+			if s == "" {
+				continue
+			}
+			spl := strings.Split(s, " ")
+			start, _ := strconv.Atoi(spl[0])
+			end, _ := strconv.Atoi(spl[1])
+
+			seeds = append(seeds, []int{start, end})
+		}
+
+		mapList := make([][][]int, 0)
+		for l := 2; l < len(lines); l++ {
+			line := lines[l]
+
+			if line == "" {
+				continue
+			}
+
+			if line[len(line)-1:] == ":" {
+				// Start a new mapping chain
+				m := make([][]int, 0)
+				for i := l + 1; i < len(lines) && lines[i] != ""; i++ {
+					m = buildOnRange(m, lines[i])
+					l += 1
+				}
+
+				mapList = append(mapList, m)
+			}
+		}
+
+		// Now go through each seed
+		lowest := math.MaxInt
+		for _, sp := range seeds {
+			for si := sp[0]; si < sp[0]+sp[1]; si++ {
+				//fmt.Printf("%v\n", sp[0]+sp[1])
+
+				sm := si
+				for _, r := range mapList {
+					mappedTo := mapRange(r, sm)
+					sm = mappedTo
+				}
+
+				if lowest > sm {
+					lowest = sm
+				}
+			}
+
+		}
+
+		return lowest
+	}
+	// solve part 1 here
+
+	lines := strings.Split(input, "\n")
+
+	seeds := strings.Split(regexp.MustCompile(`seeds: (?P<seeds>.*)`).FindStringSubmatch(lines[0])[1], " ")
+
+	mapList := make([][][]int, 0)
+	for l := 2; l < len(lines); l++ {
+		line := lines[l]
+
+		if line == "" {
+			continue
+		}
+
+		if line[len(line)-1:] == ":" {
+			// Start a new mapping chain
+			m := make([][]int, 0)
+			for i := l + 1; i < len(lines) && lines[i] != ""; i++ {
+				m = buildOnRange(m, lines[i])
+				l += 1
+			}
+
+			mapList = append(mapList, m)
+		}
+	}
+
+	// Now go through each seed
+	lowest := math.MaxInt
+	for _, s := range seeds {
+		si, _ := strconv.Atoi(s)
+
+		for _, r := range mapList {
+			mappedTo := mapRange(r, si)
+			si = mappedTo
+		}
+
+		if lowest > si {
+			lowest = si
+		}
+	}
+
+	return lowest
+}