Solve year 21/7

Author: code-shoily

README.md

@@ -24,18 +24,18 @@ I am using `embed` and `generics` to solve problems. So at least go `1.18` is ne
 
 I have not shared my inputs as it is [discouraged to share inputs](https://www.reddit.com/r/adventofcode/comments/k99rod/sharing_input_data_were_we_requested_not_to/) on public repository and I respect that. I will purge my past shares soon as I didn't know of info. 
 
-## Progress - 76.5 of 200
+## Progress - 77.5 of 200
 
 | Day | [2015](year15) | [2016](year16) | [2017](year17) | [2018](year18) | [2019](year19) | [2020](year20) | [2021](year21) | [2022](year22) |
 |:---:|:-:|:-:|:-:|:-:|:-:|:-:|:-:|:-:|
-| :star: | 37 | 26 | 15 | 11 | 12 | 18 | 17 | 15 |
+| :star: | 37 | 26 | 15 | 11 | 12 | 18 | 19 | 15 |
 |1| :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal:| :1st_place_medal: | :1st_place_medal: | :1st_place_medal: |
 |2| :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: |
 |3| :1st_place_medal: | :1st_place_medal: | | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: |
 |4| :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: |
 |5| :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: |
 |6| :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: | :1st_place_medal: |
-|7| :1st_place_medal: | :1st_place_medal: | | :2nd_place_medal: | | :1st_place_medal: | | :1st_place_medal: |
+|7| :1st_place_medal: | :1st_place_medal: | | :2nd_place_medal: | | :1st_place_medal: |  :1st_place_medal: | :1st_place_medal: |
 |8| :1st_place_medal: | | :1st_place_medal: | | | :1st_place_medal: | | |
 |9| :1st_place_medal: | | :1st_place_medal: | | | :1st_place_medal: | | |
 |10| :1st_place_medal: | | | | | | :1st_place_medal: | |

year21/README.md

@@ -12,6 +12,7 @@
 |  4  |    [Giant Squid](https://adventofcode.com/2021/day/4)    | :dizzy_face: :dizzy_face: | [year21/day04](/year21/day04) | :octopus: :slot_machine: |
 |  5  |    [Hydrothermal Venture](https://adventofcode.com/2021/day/5)    | :vomiting_face: | [year21/day05](/year21/day05) | :straight_ruler: :triangular_ruler: |
 |  6  |    [Lanternfish](https://adventofcode.com/2021/day/6)    | :star2: | [year21/day06](/year21/day06) | :bucket: :lantern: :heavy_multiplication_x: :fish: |
+|  7  |    [The Treachery of Whales](https://adventofcode.com/2021/day/7)    | :star2: | [year21/day07](/year21/day07) | :crab: :fuelpump: :arrow_left: :arrow_right: |
 |  10  |    [Syntax Scoring](https://adventofcode.com/2021/day/10)    | :star2: | [year21/day10](/year21/day10) | :interrobang:  |
 |  11  |    [Dumbo Octopus](https://adventofcode.com/2021/day/11)    | :star2: | [year21/day11](/year21/day11) | :octopus: :flashlight: |
 |  25  |    [Sea Cucumber](https://adventofcode.com/2021/day/25)    | :star2: :star2: | [year21/day25](/year21/day25) | :cucumber: :ocean: |

year21/day07/main.go

@@ -0,0 +1,56 @@
+// Package day07 - Solution for Advent of Code 2021/07
+// Problem Link: http://adventofcode.com/2021/day/07
+package day07
+
+import (
+	_ "embed"
+	"fmt"
+	"github.com/code-shoily/aocgo/algo"
+	"math"
+	"strconv"
+	"strings"
+)
+
+//go:embed input.txt
+var input string
+
+// Run prints out the result of the solution.
+func Run() {
+	fmt.Println(solve(input))
+}
+
+func solve(input string) (int, int) {
+	data := parse(input)
+	return solvePart1(data), solvePart2(data)
+}
+
+func solvePart1(positions []int) (fuelCost int) {
+	median := algo.Median(positions)
+
+	for _, pos := range positions {
+		fuelCost += int(math.Abs(float64(pos) - median))
+	}
+
+	return fuelCost
+}
+
+func solvePart2(positions []int) (fuelCost int) {
+	mean := math.Round(algo.Mean(positions))
+
+	for _, pos := range positions {
+		diff := math.Abs(float64(pos)-mean) + 1
+		fuelCost += int(diff * (diff - 1) / 2)
+	}
+
+	return fuelCost
+}
+
+func parse(input string) (positions []int) {
+	for _, token := range strings.Split(input, ",") {
+		if position, err := strconv.Atoi(token); err == nil {
+			positions = append(positions, position)
+		}
+	}
+
+	return positions
+}

year21/day07/main_test.go

@@ -0,0 +1,38 @@
+package day07
+
+import (
+	"testing"
+)
+
+func TestSolve(t *testing.T) {
+	solve1, solve2 := solve(input)
+	expected1, expected2 := 344_138, 94_862_124
+
+	if solve1 != expected1 {
+		t.Errorf("Fail - part 1. Expected %v, got %v", expected1, solve1)
+	}
+
+	if solve2 != expected2 {
+		t.Errorf("Fail - part 2. Expected %v, got %v", expected2, solve2)
+	}
+}
+
+func BenchmarkSolve(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		solve(input)
+	}
+}
+
+func BenchmarkSolvePart1(b *testing.B) {
+	data := parse(input)
+	for i := 0; i < b.N; i++ {
+		solvePart1(data)
+	}
+}
+
+func BenchmarkSolvePart2(b *testing.B) {
+	data := parse(input)
+	for i := 0; i < b.N; i++ {
+		solvePart2(data)
+	}
+}

year21/runner.go

@@ -8,6 +8,7 @@ import (
 	"github.com/code-shoily/aocgo/year21/day04"
 	"github.com/code-shoily/aocgo/year21/day05"
 	"github.com/code-shoily/aocgo/year21/day06"
+	"github.com/code-shoily/aocgo/year21/day07"
 	"github.com/code-shoily/aocgo/year21/day10"
 	"github.com/code-shoily/aocgo/year21/day11"
 	"github.com/code-shoily/aocgo/year21/day25"
@@ -27,6 +28,8 @@ func SolveForDay(day int) {
 		day05.Run()
 	case 6:
 		day06.Run()
+	case 7:
+		day07.Run()
 	case 10:
 		day10.Run()
 	case 11: