feat(spans): Add Contains()

Author: angch

angch/2025-05/main.go

@@ -6,7 +6,6 @@ import (
 	"log"
 	"os"
 	"strconv"
-	"strings"
 	"time"
 
 	"github.com/angch/adventofcode/angch/span"
@@ -20,42 +19,28 @@ func day5(file string) (part1, part2 int) {
 	defer f.Close()
 	scanner := bufio.NewScanner(f)
 
-	spans := [][2]int{}
+	spans := span.NewSpans[bool]()
 	for scanner.Scan() {
 		t := scanner.Text()
-		_ = t
 		if t == "" {
 			break
 		}
-		l_, r_, ok := strings.Cut(t, "-")
-		_ = ok
-		l, _ := strconv.Atoi(l_)
-		r, _ := strconv.Atoi(r_)
-		spans = append(spans, [2]int{l, r})
+		l, r := 0, 0
+		fmt.Sscanf(t, "%d-%d", &l, &r)
+		spans = spans.AddCompress(l, r, true)
 	}
-	// log.Println(spans)
 
 	for scanner.Scan() {
 		t := scanner.Text()
-		_ = t
 		i, _ := strconv.Atoi(t)
-		for _, v := range spans {
-			if i >= v[0] && i <= v[1] {
-				part1++
-				break
-			}
+		if spans.Contains(i) {
+			part1++
 		}
 	}
 
-	s2 := span.NewSpans[bool]()
 	for _, v := range spans {
-		s2 = s2.AddCompress(v[0], v[1], true)
-		log.Printf("%+v\n", s2)
-	}
-	for _, v := range s2 {
 		part2 += v.To - v.From + 1
 	}
-
 	return
 }
 

angch/span/span.go

@@ -83,4 +83,27 @@ compress:
 	return s
 }
 
+func (s Spans[T]) Contains(i int) bool {
+	// binary search
+	l, r := 0, len(s)
+	for l < r {
+		mid := l + (r-l)/2
+
+		if mid >= len(s) {
+			return false
+		}
+
+		diff := s[mid].From - i
+		if diff <= 0 && s[mid].To >= i {
+			return true
+		}
+		if diff <= 0 {
+			l = mid + 1
+		} else {
+			r = mid
+		}
+	}
+	return false
+}
+
 // Initial conversion from 2022-15 code to type param'd Spans