AoC Day 9, Part 1 (Solved)

2023/09/code.go

@@ -0,0 +1,78 @@
+package main
+
+import (
+	"strconv"
+	"strings"
+
+	"github.com/jpillora/puzzler/harness/aoc"
+)
+
+func main() {
+	aoc.Harness(run)
+}
+
+// on code change, run will be executed 4 times:
+// 1. with: false (part1), and example input
+// 2. with: true (part2), and example input
+// 3. with: false (part1), and user input
+// 4. with: true (part2), and user input
+// the return value of each run is printed to stdout
+func run(part2 bool, input string) any {
+	// when you're ready to do part 2, remove this "not implemented" block
+	data := make([][]int, 0)
+
+	for _, line := range strings.Split(input, "\n") {
+		dataLine := make([]int, 0)
+		for _, s := range strings.Split(line, " ") {
+			d, _ := strconv.Atoi(s)
+			dataLine = append(dataLine, d)
+		}
+		data = append(data, dataLine)
+	}
+
+	if part2 {
+		return "not implemented"
+	}
+	// solve part 1 here
+
+	sumNexts := 0
+	for _, d := range data {
+		sumNexts += getNext(d)
+	}
+
+	return sumNexts
+}
+
+func getNext(data []int) int {
+	diffTriangle := make([][]int, 0)
+	diffTriangle = append(diffTriangle, data)
+
+	for !allZero(diffTriangle[len(diffTriangle)-1]) {
+		diffTriangle = append(diffTriangle, getDiffs(diffTriangle[len(diffTriangle)-1]))
+		//fmt.Printf("%v\n", diffTriangle[len(diffTriangle)-1])
+	}
+
+	add := 0
+	for i := len(diffTriangle) - 2; i >= 0; i -= 1 {
+		add += diffTriangle[i][len(diffTriangle[i])-1]
+	}
+
+	return add
+}
+
+func getDiffs(data []int) []int {
+	nextData := make([]int, 0)
+	for i := 0; i < len(data)-1; i += 1 {
+		nextData = append(nextData, data[i+1]-data[i])
+	}
+	return nextData
+}
+
+func allZero(data []int) bool {
+	for _, d := range data {
+		if d != 0 {
+			return false
+		}
+	}
+	return true
+}