2020 day5 - ugh off by one w/ funky binary search

2020/day05/main.go

@@ -3,9 +3,9 @@ package main
 import (
 	"flag"
 	"fmt"
+	"io/ioutil"
+	"log"
 	"strings"
-
-	"github.com/alexchao26/advent-of-code-go/util"
 )
 
 func main() {
@@ -14,38 +14,100 @@ func main() {
 	flag.Parse()
 	fmt.Println("Running part", part)
 
+	bytes, err := ioutil.ReadFile("input.txt")
+	if err != nil {
+		log.Fatalf("Reading file: %s", err)
+	}
+
 	if part == 1 {
-		ans := part1(util.ReadFile("./input.txt"))
-		util.CopyToClipboard(fmt.Sprintf("%v", ans))
+		ans := part1(string(bytes))
 		fmt.Println("Output:", ans)
 	} else {
-		ans := part2(util.ReadFile("./input.txt"))
-		util.CopyToClipboard(fmt.Sprintf("%v", ans))
+		ans := part2(string(bytes))
 		fmt.Println("Output:", ans)
 	}
 }
 
 func part1(input string) int {
-	parsed := parseInput(input)
-	_ = parsed
+	var best int
+	for _, seatDetails := range strings.Split(input, "\n") {
+		if len(seatDetails) == 0 {
+			continue
+		}
+		rowLeft, rowRight := 0, 127
+		for _, char := range seatDetails[0:6] {
+			if char == 'F' {
+				rowRight -= (rowRight - rowLeft + 1) / 2
+			} else {
+				rowLeft += (rowRight - rowLeft + 1) / 2
+			}
+		}
+		if seatDetails[6] == 'B' {
+			rowLeft = rowRight
+		}
 
-	return 0
+		colLeft, colRight := 0, 7
+		for _, col := range seatDetails[7:9] {
+			if col == 'L' {
+				colRight -= (colRight - colLeft + 1) / 2
+			} else {
+				colLeft += (colRight - colLeft + 1) / 2
+			}
+		}
+
+		if seatDetails[9] == 'R' {
+			colLeft = colRight
+		}
+
+		id := rowLeft*8 + colLeft
+		if id > best {
+			best = id
+		}
+	}
+
+	return best
 }
 
 func part2(input string) int {
-	parsed := parseInput(input)
-	_ = parsed
+	allSeatIDs := make(map[int]bool)
 
-	return 0
-}
+	for _, seatDetails := range strings.Split(input, "\n") {
+		rowLeft, rowRight := 0, 127
+		for _, char := range seatDetails[0:6] {
+			if char == 'F' {
+				rowRight -= (rowRight - rowLeft + 1) / 2
+			} else {
+				rowLeft += (rowRight - rowLeft + 1) / 2
+			}
+		}
+		if seatDetails[6] == 'B' {
+			rowLeft = rowRight
+		}
 
-func parseInput(input string) []int {
-	var ans []int
+		colLeft, colRight := 0, 7
+		for _, col := range seatDetails[7:9] {
+			if col == 'L' {
+				colRight -= (colRight - colLeft + 1) / 2
+			} else {
+				colLeft += (colRight - colLeft + 1) / 2
+			}
+		}
 
-	lines := strings.Split(input, "\n")
-	for _, l := range lines {
-		ans = append(ans, util.StrToInt(l))
+		if seatDetails[9] == 'R' {
+			colLeft = colRight
+		}
+
+		id := rowLeft*8 + colLeft
+		allSeatIDs[id] = true
 	}
 
-	return ans
+	var mySeatID int
+	for id := range allSeatIDs {
+		if allSeatIDs[id] && allSeatIDs[id+2] && !allSeatIDs[id+1] {
+			mySeatID = id + 1
+			break
+		}
+	}
+
+	return mySeatID
 }