day 5 part 1 test passes

day05.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
+type day05 struct{}
+
+type seedmap struct {
+	original int64
+	previous int64
+	current  int64
+}
+
+func readseeds(line string) []seedmap {
+	seeds := make([]seedmap, 0, 10)
+	scanner := bufio.NewScanner(strings.NewReader(line))
+	scanner.Split(bufio.ScanWords)
+
+	for scanner.Scan() {
+		val, _ := strconv.ParseInt(scanner.Text(), 10, 64)
+		seeds = append(seeds, seedmap{original: val, current: val, previous: val})
+	}
+
+	return seeds
+}
+
+func updateseeds(line string, seeds []seedmap) []seedmap {
+	input := strings.SplitN(line, " ", 3)
+	dst, _ := strconv.ParseInt(input[0], 10, 64)
+	src, _ := strconv.ParseInt(input[1], 10, 64)
+	rng, _ := strconv.ParseInt(input[2], 10, 64)
+
+	for i, seed := range seeds {
+		if seed.current >= src && seed.current <= src+rng && seed.current == seed.previous {
+			seeds[i].current = seed.current + (dst - src)
+		}
+	}
+	return seeds
+}
+
+func minint64(x, y int64) int64 {
+	if x > y {
+		return y
+	}
+	return x
+}
+
+func (d day05) solve1(r io.Reader) string {
+	scanner := bufio.NewScanner(r)
+
+	scanner.Scan()
+	_, seedline, _ := strings.Cut(scanner.Text(), ": ")
+	seeds := readseeds(seedline)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		if strings.HasSuffix(line, "map:") || line == "" {
+			for i := range seeds {
+				seeds[i].previous = seeds[i].current
+			}
+			continue
+		}
+		seeds = updateseeds(scanner.Text(), seeds)
+	}
+
+	min := minint64(seeds[0].current, seeds[1].current)
+	for i := 2; i < len(seeds); i++ {
+		min = minint64(min, seeds[i].current)
+	}
+
+	return fmt.Sprintf("%d", min)
+}
+
+func (d day05) solve2(r io.Reader) string {
+	return "incomplete"
+}

main_test.go

@@ -104,3 +104,48 @@ Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11`
 	}
 
 }
+
+func TestDay05(t *testing.T) {
+	input := `seeds: 79 14 55 13
+
+seed-to-soil map:
+50 98 2
+52 50 48
+
+soil-to-fertilizer map:
+0 15 37
+37 52 2
+39 0 15
+
+fertilizer-to-water map:
+49 53 8
+0 11 42
+42 0 7
+57 7 4
+
+water-to-light map:
+88 18 7
+18 25 70
+
+light-to-temperature map:
+45 77 23
+81 45 19
+68 64 13
+
+temperature-to-humidity map:
+0 69 1
+1 0 69
+
+humidity-to-location map:
+60 56 37
+56 93 4`
+
+	puzzle := day05{}
+
+	ans := "35"
+	res := puzzle.solve1(strings.NewReader(input))
+	if ans != res {
+		t.Errorf("solve1() = %s; wanted %s", res, ans)
+	}
+
+}