2024 02 optimized bruteforce. No time to debug linear solution, it's …

…almost there

2024/02-Red-Nosed-Reports/input_pub.txt

@@ -0,0 +1,6 @@
+7 6 4 2 1
+1 2 7 8 9
+9 7 6 2 1
+1 3 2 4 5
+8 6 4 4 1
+1 3 6 7 9

2024/02-Red-Nosed-Reports/main.go

@@ -0,0 +1,123 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+)
+
+func read(f string) [][]int {
+	res := [][]int{}
+	s, _ := os.ReadFile(f)
+	lines := strings.Split(string(s), "\n")
+	for _, l := range lines {
+		line := strings.Split(l, " ")
+		levels := []int{}
+		for i := range line {
+			n, _ := strconv.ParseInt(line[i], 10, 32)
+			levels = append(levels, int(n))
+		}
+		res = append(res, levels)
+	}
+	return res
+}
+
+func safeReport(r []int) bool {
+	safe := true
+	if r[0] == r[1] {
+		return false
+	}
+	sign := (r[1] - r[0]) / abs(r[1]-r[0])
+	for i := range len(r) - 1 {
+		d := r[i+1] - r[i]
+		if d == 0 || abs(d) > 3 || sign != (d/abs(d)) {
+			safe = false
+			break
+		}
+	}
+	return safe
+}
+
+func solve(f string) (p1, p2 int) {
+	reports := read(f)
+	for _, r := range reports {
+		safe := safeReport(r)
+		if safe {
+			p1++
+		}
+
+		for i := range r {
+			rProbe := make([]int, len(r)-1)
+			copy(rProbe, r[:i])
+			copy(rProbe[i:], r[i+1:])
+			if safeReport(rProbe) {
+				p2++
+				break
+			}
+		}
+	}
+
+	return p1, p2
+}
+
+// func almost_linear_solution(f string) (p1, p2 int) {
+// 	reports := read(f)
+// 	for _, r := range reports {
+// 		fmt.Println(r)
+
+// 		fails := 0
+// 		failed := true // presume
+// 		for {
+
+// 			if len(r) <= 2 || !failed || fails > 1 {
+// 				break
+// 			}
+// 			failed = false
+// 			for i := 1; i < len(r)-1; i++ {
+// 				if r[i-1] == r[i] || r[i] == r[i+1] ||
+// 					abs(r[i]-r[i-1]) > 3 || abs(r[i+1]-r[i]) > 3 ||
+// 					sign(r[i]-r[i-1]) != sign(r[i+1]-r[i]) {
+// 					r = slices.Delete(r, i, i+1)
+// 					fails++
+// 					failed = true
+// 					break
+// 				}
+// 			}
+// 		}
+// 		if fails == 0 {
+// 			p1++
+// 		}
+// 		if fails <= 1 {
+// 			p2++
+// 		}
+// 		if fails >= 1 {
+// 			fmt.Println(r, fails)
+// 			fmt.Println()
+// 		}
+
+// 	}
+// 	return p1, p2
+// }
+
+func main() {
+	start := time.Now()
+	fmt.Println("Day 02: Red-Nosed Reports")
+	// p1, p2 := solve("input_pub.txt")
+	p1, p2 := solve("../aoc-inputs/2024/02/input.txt")
+	fmt.Println("\tPart One:", p1) // 680
+	fmt.Println("\tPart Two:", p2) // 710
+	fmt.Printf("Done in %.3f seconds \n", time.Since(start).Seconds())
+}
+
+func abs[T int | int64](n T) T {
+	if n < 0 {
+		return -n
+	}
+	return n
+}
+
+func sign[T int | int64](n T) T {
+	return n / abs(n)
+}