AoC 2020: day4

Signed-off-by: Ettore Dreucci <ettore.dreucci@gmail.com>

2018-go/day_06/input

@@ -0,0 +1,50 @@
+81, 46
+330, 289
+171, 261
+248, 97
+142, 265
+139, 293
+309, 208
+315, 92
+72, 206
+59, 288
+95, 314
+126, 215
+240, 177
+78, 64
+162, 168
+75, 81
+271, 258
+317, 223
+210, 43
+47, 150
+352, 116
+316, 256
+269, 47
+227, 343
+125, 290
+245, 310
+355, 301
+251, 282
+353, 107
+254, 298
+212, 128
+60, 168
+318, 254
+310, 303
+176, 345
+110, 109
+217, 338
+344, 330
+231, 349
+259, 208
+201, 57
+200, 327
+354, 111
+166, 214
+232, 85
+96, 316
+151, 288
+217, 339
+62, 221
+307, 68

2018-go/day_06/main.go

@@ -0,0 +1,133 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"math"
+	"os"
+)
+
+type point struct {
+	x  int
+	y  int
+	id int
+}
+
+type grid struct {
+	points      [][]int
+	coordinates []point
+	currentID   int
+	invalidIDs  map[int]bool
+	maxX        int
+	maxY        int
+	minX        int
+	minY        int
+	maxArea     int
+}
+
+func (p1 point) manhattanDistance(p2 point) int {
+	return int(math.Abs(float64(p1.x-p2.x)) + math.Abs(float64(p1.y-p2.y)))
+}
+
+func main() {
+	var currentGrid grid
+
+	file, err := os.Open("./input")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer file.Close()
+
+	scan := bufio.NewScanner(file)
+	for scan.Scan() {
+		var p point
+
+		line := scan.Text()
+		fmt.Sscanf(line, "%d, %d", &p.x, &p.y)
+		p.id = currentGrid.currentID
+		currentGrid.currentID++
+
+		currentGrid.coordinates = append(currentGrid.coordinates, p)
+
+		if p.x > currentGrid.maxX {
+			currentGrid.maxX = p.x
+		}
+		if p.y > currentGrid.maxY {
+			currentGrid.maxY = p.y
+		}
+		if p.x < currentGrid.minX || currentGrid.minX == 0 {
+			currentGrid.minX = p.x
+		}
+		if p.y < currentGrid.minY || currentGrid.minY == 0 {
+			currentGrid.minY = p.y
+		}
+	}
+
+	currentGrid.points = make([][]int, currentGrid.maxX)
+	for i := range currentGrid.points {
+		currentGrid.points[i] = make([]int, currentGrid.maxY)
+	}
+
+	for x := 0; x < currentGrid.maxX; x++ {
+		for y := 0; y < currentGrid.maxY; y++ {
+			minDist := -1
+			minDistID := -1
+			for i, c := range currentGrid.coordinates {
+				dist := c.manhattanDistance(point{x: x, y: y})
+				if i == 0 {
+					minDist = dist
+					minDistID = c.id
+				} else if dist < minDist {
+					minDist = dist
+					minDistID = c.id
+				} else if dist == minDist {
+					minDistID = -1
+				}
+			}
+			currentGrid.points[x][y] = minDistID
+		}
+	}
+
+	currentGrid.invalidIDs = make(map[int]bool)
+	for x := 0; x < currentGrid.maxX; x++ {
+		currentGrid.invalidIDs[currentGrid.points[x][0]] = true
+		currentGrid.invalidIDs[currentGrid.points[x][currentGrid.maxY-1]] = true
+	}
+	for y := 0; y < currentGrid.maxY; y++ {
+		currentGrid.invalidIDs[currentGrid.points[0][y]] = true
+		currentGrid.invalidIDs[currentGrid.points[currentGrid.maxX-1][y]] = true
+	}
+
+	for id := 0; id < currentGrid.currentID; id++ {
+		count := 0
+		for x := 0; x < currentGrid.maxX; x++ {
+			for y := 0; y < currentGrid.maxY; y++ {
+				if currentGrid.points[x][y] == id {
+					count++
+				}
+			}
+		}
+		if count > currentGrid.maxArea {
+			_, invalidID := currentGrid.invalidIDs[id]
+			if !invalidID {
+				currentGrid.maxArea = count
+			}
+		}
+	}
+	fmt.Printf("Part One: %v\n", currentGrid.maxArea)
+
+	count := 0
+	for x := 0; x < currentGrid.maxX; x++ {
+		for y := 0; y < currentGrid.maxY; y++ {
+			sum := 0
+			for _, c := range currentGrid.coordinates {
+				sum += c.manhattanDistance(point{x: x, y: y})
+			}
+			if sum < 10000 {
+				count++
+			}
+		}
+	}
+	fmt.Printf("Part Two: %v\n", count)
+}