From 11405e23c80d4ec87be3480dc8b4a54d153ead6c Mon Sep 17 00:00:00 2001
From: Luke Else <mail@luke-else.co.uk>
Date: Thu, 16 Dec 2021 20:33:01 +0000
Subject: [PATCH] day 15b complete

---
 day15/15b/main.go | 117 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 117 insertions(+)
 create mode 100644 day15/15b/main.go

diff --git a/day15/15b/main.go b/day15/15b/main.go
new file mode 100644
index 0000000..8978780
--- /dev/null
+++ b/day15/15b/main.go
@@ -0,0 +1,117 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+
+	"github.com/yourbasic/graph"
+)
+
+func main() {
+	content := returnContent("../input")
+	//content := returnContent("../testInput")
+
+	height := len(*content)
+	width := len((*content)[0])
+
+	fullHeight := 5 * height
+	fullWidth := 5 * width
+	g := graph.New(fullHeight * fullWidth)
+
+	for y := 0; y < fullHeight; y++ {
+		for x := 0; x < fullWidth; x++ {
+			c := Coordinate{
+				X: x,
+				Y: y,
+			}
+			myIdx := c.Y*fullWidth + c.X
+			neighbours := c.Neighbours(fullWidth, fullHeight, false)
+			for _, neighbour := range neighbours {
+				neighbourCost := int64((*content)[neighbour.Y%height][neighbour.X%width])
+				widthPenalty := neighbour.X / width
+				heightPenalty := neighbour.Y / height
+				neighbourCost += int64(widthPenalty + heightPenalty)
+				for neighbourCost > 9 {
+					neighbourCost -= 9
+				}
+
+				neighborIdx := neighbour.Y*fullWidth + neighbour.X
+				g.AddCost(myIdx, neighborIdx, neighbourCost)
+			}
+		}
+	}
+
+	_, cost := graph.ShortestPath(g, 0, fullWidth*fullHeight-1)
+
+	fmt.Println(cost)
+}
+
+type Coordinate struct {
+	X int
+	Y int
+}
+
+func (c *Coordinate) Neighbours(gridWidth int, gridHeight int, diagonal bool) (out []Coordinate) {
+	spaceLeft := c.X > 0
+	spaceRight := c.X < gridWidth-1
+	spaceUp := c.Y > 0
+	spaceDown := c.Y < gridHeight-1
+
+	if spaceLeft {
+		out = append(out, Coordinate{c.X - 1, c.Y})
+	}
+	if spaceRight {
+		out = append(out, Coordinate{c.X + 1, c.Y})
+	}
+	if spaceUp {
+		out = append(out, Coordinate{c.X, c.Y - 1})
+	}
+	if spaceDown {
+		out = append(out, Coordinate{c.X, c.Y + 1})
+	}
+
+	if diagonal {
+		if spaceUp && spaceLeft {
+			out = append(out, Coordinate{c.X - 1, c.Y - 1})
+		}
+		if spaceUp && spaceRight {
+			out = append(out, Coordinate{c.X + 1, c.Y - 1})
+		}
+		if spaceDown && spaceLeft {
+			out = append(out, Coordinate{c.X - 1, c.Y + 1})
+		}
+		if spaceDown && spaceRight {
+			out = append(out, Coordinate{c.X + 1, c.Y + 1})
+		}
+	}
+
+	return
+}
+
+func returnContent(path string) *[][]int {
+	//read file and return it as an array of integers
+
+	file, err := os.Open(path)
+	var content [][]int
+
+	if err != nil {
+		fmt.Println("Unlucky, the file didn't open")
+		return &content
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+
+	for scanner.Scan() {
+		nums := []int{}
+		for _, num := range scanner.Text() {
+			val, _ := strconv.Atoi(string(num))
+			nums = append(nums, val)
+		}
+		content = append(content, nums)
+	}
+
+	return &content
+}