Add 2021-05 in Golang

Signed-off-by: AKU <tom@tdpain.net>

challenges/2021/05-hydrothermalVenture/go/challenge.go

@@ -0,0 +1,136 @@
+package challenge
+
+import (
+	"strconv"
+	"strings"
+
+	"github.com/codemicro/adventOfCode/lib/aocgo"
+)
+
+type Point struct {
+	x int
+	y int
+}
+
+func pointFromString(input string) (*Point, error) {
+	sp := strings.Split(input, ",")
+	x, err := strconv.Atoi(sp[0])
+	if err != nil {
+		return nil, err
+	}
+	y, err := strconv.Atoi(sp[1])
+	if err != nil {
+		return nil, err
+	}
+	return &Point{x: x, y: y}, nil
+}
+
+type Line [2]*Point
+
+func parse(instr string) ([]Line, error) {
+	var o []Line
+	for _, line := range strings.Split(strings.TrimSpace(instr), "\n") {
+		sp := strings.Split(line, " -> ")
+		p1, err := pointFromString(sp[0])
+		if err != nil {
+			return nil, err
+		}
+		p2, err := pointFromString(sp[1])
+		if err != nil {
+			return nil, err
+		}
+		o = append(o, Line{p1, p2})
+	}
+	return o, nil
+}
+
+func removeDiagonalLines(lines []Line) []Line {
+	var n int
+	for _, line := range lines {
+		if line[0].x == line[1].x || line[0].y == line[1].y {
+			lines[n] = line
+			n += 1
+		}
+	}
+	return lines[:n]
+}
+
+func iteratePoints(line Line) chan *Point {
+
+	p1 := line[0]
+	p2 := line[1]
+
+	delta_x := p2.x - p1.x
+	delta_y := p2.y - p1.y
+
+	var xStep, yStep int
+
+	if delta_x > 0 {
+		xStep = 1
+	} else if delta_x < 0 {
+		xStep = -1
+	}
+
+	if delta_y > 0 {
+		yStep = 1
+	} else if delta_y < 0 {
+		yStep = -1
+	}
+
+	c := make(chan *Point)
+
+	go func() {
+		c <- p1
+		lastPoint := *p1
+		for lastPoint != *p2 {
+			np := &Point{
+				x: lastPoint.x + xStep,
+				y: lastPoint.y + yStep,
+			}
+			c <- np
+			lastPoint = *np
+		}
+		close(c)
+	}()
+
+	return c
+}
+
+func countOverlappingPoints(lines []Line) int {
+	areas := make(map[Point]int)
+	for _, line := range lines {
+		for point := range iteratePoints(line) {
+			t := *point
+			areas[t] = areas[t] + 1
+		}
+	}
+
+	var numberOverlaps int
+	for _, n := range areas {
+		if n > 1 {
+			numberOverlaps += 1
+		}
+	}
+	return numberOverlaps
+}
+
+type Challenge struct {
+	aocgo.BaseChallenge
+}
+
+func (c Challenge) One(instr string) (interface{}, error) {
+	lines, err := parse(instr)
+	if err != nil {
+		return nil, err
+	}
+	lines = removeDiagonalLines(lines)
+	return countOverlappingPoints(lines), nil
+}
+
+func (c Challenge) Two(instr string) (interface{}, error) {
+	lines, err := parse(instr)
+	if err != nil {
+		return nil, err
+	}
+	return countOverlappingPoints(lines), nil
+}

challenges/2021/README.md

@@ -14,7 +14,7 @@ Solutions to the [2021 Advent of Code](https://adventofcode.com/2021).
 | 02 - Dive!                          | Complete           | [Python](02-dive/py), [Go](02-dive/go)                                       | Have this set of instructions and do something sensible with it. |
 | 03 - Binary Diagnostic              | Complete           | [Python](03-binaryDiagnostic/py), [Nim](03-binaryDiagnostic/nim)             | Bit twiddling aplenty!                                           |
 | 04 - Giant Squid                    | Complete           | [Python](04-giantSquid/py)                                                   | B-I-N-G-O, B-I-N-G-O, B-I-N-G-O and Bingo was his name-o!        |
-| 05 - Hydrothermal Venture           | Complete           | [Python](05-hydrothermalVenture/py)                                          | Pointy.                                                          |
+| 05 - Hydrothermal Venture           | Complete           | [Python](05-hydrothermalVenture/py), [Go](05-hydrothermalVenture/go)         | Pointy.                                                          |
 
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