Attempt 5

2025/five/five.go

@@ -0,0 +1,101 @@
+package main
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type freshRange struct {
+	start, end int
+}
+
+func (r *freshRange) contains(c int) bool {
+	return c >= r.start && c <= r.end
+}
+
+func (r *freshRange) nInRange() int {
+	return (r.end - r.start) + 1
+}
+
+func check(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
+
+func getRanges(scanner *bufio.Scanner) (ranges []freshRange, err error) {
+	ranges = make([]freshRange, 0, 5)
+
+	for scanner.Scan() {
+		text := scanner.Text()
+
+		if text == "" {
+			return ranges, nil
+		}
+
+		startEnd := strings.Split(text, "-")
+
+		if len(startEnd) != 2 {
+			return nil, errors.New("Fresh range does not contain exactly two numbers")
+		}
+
+		start, err := strconv.Atoi(startEnd[0])
+		if err != nil {
+			return nil, err
+		}
+
+		end, err := strconv.Atoi(startEnd[1])
+		if err != nil {
+			return nil, err
+		}
+
+		ranges = append(ranges, freshRange{start, end})
+	}
+	return nil, errors.New("No empty line in file to delimit fresh ranges")
+}
+
+func main() {
+
+	file, err := os.Open("five.txt")
+	check(err)
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	ranges, err := getRanges(scanner)
+	check(err)
+
+	authRanges := make([]freshRange, 1, len(ranges))
+	authRanges[0] = ranges[0]
+
+RANGE:
+	for _, r := range ranges {
+
+		for _, authR := range authRanges {
+			if authR.contains(r.start) {
+				if r.end > authR.end {
+					authR.end = r.end
+				}
+				continue RANGE
+			}
+
+			if authR.contains(r.end) {
+				if r.start < authR.start {
+					authR.start = r.start
+				}
+				continue RANGE
+			}
+		}
+		authRanges = append(authRanges, r)
+	}
+
+	potentialNFresh := 0
+	for _, r := range authRanges {
+		potentialNFresh += r.nInRange()
+	}
+
+	fmt.Printf("N raw %d and consolidated %d. %d potential fresh ingredients.\n", len(ranges), len(authRanges), potentialNFresh)
+}