From 7a8155b60690f23eecc2bea1efba029ca6febc94 Mon Sep 17 00:00:00 2001
From: alexchao26 <alexchaoo@gmail.com>
Date: Sat, 26 Dec 2020 02:25:48 -0500
Subject: [PATCH] 2015-day06: grid toggling/incrementing & decrementing

---
 2015/day06/main.go      | 119 ++++++++++++++++++++++++++++++++++++++++
 2015/day06/main_test.go |  41 ++++++++++++++
 2 files changed, 160 insertions(+)
 create mode 100644 2015/day06/main.go
 create mode 100644 2015/day06/main_test.go

diff --git a/2015/day06/main.go b/2015/day06/main.go
new file mode 100644
index 0000000..fbcb4a0
--- /dev/null
+++ b/2015/day06/main.go
@@ -0,0 +1,119 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"strings"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+func main() {
+	var part int
+	flag.IntVar(&part, "part", 1, "part 1 or 2")
+	flag.Parse()
+	fmt.Println("Running part", part)
+
+	var ans int
+	if part == 1 {
+		ans = part1(util.ReadFile("./input.txt"))
+	} else {
+		ans = part2(util.ReadFile("./input.txt"))
+	}
+	fmt.Println("Output:", ans)
+}
+
+func part1(input string) int {
+	// 1000x1000 grid
+	grid := make([][]bool, 1000)
+	for i := range grid {
+		grid[i] = make([]bool, 1000)
+	}
+
+	for _, line := range strings.Split(input, "\n") {
+		switch {
+		case strings.HasPrefix(line, "toggle"):
+			var row1, col1, row2, col2 int
+			fmt.Sscanf(line, "toggle %d,%d through %d,%d", &row1, &col1, &row2, &col2)
+			for i := row1; i <= row2; i++ {
+				for j := col1; j <= col2; j++ {
+					grid[i][j] = !grid[i][j]
+				}
+			}
+		case strings.HasPrefix(line, "turn on"):
+			var row1, col1, row2, col2 int
+			fmt.Sscanf(line, "turn on %d,%d through %d,%d", &row1, &col1, &row2, &col2)
+			for i := row1; i <= row2; i++ {
+				for j := col1; j <= col2; j++ {
+					grid[i][j] = true
+				}
+			}
+		case strings.HasPrefix(line, "turn off"):
+			var row1, col1, row2, col2 int
+			fmt.Sscanf(line, "turn off %d,%d through %d,%d", &row1, &col1, &row2, &col2)
+			for i := row1; i <= row2; i++ {
+				for j := col1; j <= col2; j++ {
+					grid[i][j] = false
+				}
+			}
+		default:
+			panic("unhandled instruction")
+		}
+	}
+	var count int
+	for _, row := range grid {
+		for _, b := range row {
+			if b {
+				count++
+			}
+		}
+	}
+	return count
+}
+
+func part2(input string) int {
+	grid := make([][]int, 1000)
+	for i := range grid {
+		grid[i] = make([]int, 1000)
+	}
+
+	for _, line := range strings.Split(input, "\n") {
+		switch {
+		case strings.HasPrefix(line, "toggle"):
+			var row1, col1, row2, col2 int
+			fmt.Sscanf(line, "toggle %d,%d through %d,%d", &row1, &col1, &row2, &col2)
+			for i := row1; i <= row2; i++ {
+				for j := col1; j <= col2; j++ {
+					grid[i][j] += 2
+				}
+			}
+		case strings.HasPrefix(line, "turn on"):
+			var row1, col1, row2, col2 int
+			fmt.Sscanf(line, "turn on %d,%d through %d,%d", &row1, &col1, &row2, &col2)
+			for i := row1; i <= row2; i++ {
+				for j := col1; j <= col2; j++ {
+					grid[i][j]++
+				}
+			}
+		case strings.HasPrefix(line, "turn off"):
+			var row1, col1, row2, col2 int
+			fmt.Sscanf(line, "turn off %d,%d through %d,%d", &row1, &col1, &row2, &col2)
+			for i := row1; i <= row2; i++ {
+				for j := col1; j <= col2; j++ {
+					if grid[i][j] > 0 {
+						grid[i][j]--
+					}
+				}
+			}
+		default:
+			panic("unhandled instruction")
+		}
+	}
+	var brightness int
+	for _, row := range grid {
+		for _, v := range row {
+			brightness += v
+		}
+	}
+	return brightness
+}
diff --git a/2015/day06/main_test.go b/2015/day06/main_test.go
new file mode 100644
index 0000000..cb64f08
--- /dev/null
+++ b/2015/day06/main_test.go
@@ -0,0 +1,41 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+func Test_part1(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{"actual", util.ReadFile("input.txt"), 400410},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := part1(tt.input); got != tt.want {
+				t.Errorf("part1() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_part2(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{"actual", util.ReadFile("input.txt"), 15343601},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := part2(tt.input); got != tt.want {
+				t.Errorf("part2() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}