doukakuE18 golang http://nabetani.sakura.ne.jp/hena/orde18twintri/

main.go

package main

import (
	"fmt"
	"strconv"
	"strings"
)

type Triangle struct {
	x, y int
	d    string
	h    int
}

type Range struct {
	min, max int
}

type Output = int

func main() {
	ret := Solve("7,0R6/3,1B5")
	fmt.Printf("%v : %v", ret, "15")
}

func Solve(input string) string {
	return format(solve(parse(input)))
}

func parse(s string) (Triangle, Triangle) {
	r := strings.NewReplacer("R", ",R,", "L", ",L,", "T", ",T,", "B", ",B,", "/", ",")
	ab := strings.Split(r.Replace(s), ",")
	return parse_(ab[0:4]), parse_(ab[4:8])
}

func parse_(ss []string) Triangle {
	x, _ := strconv.Atoi(ss[0])
	y, _ := strconv.Atoi(ss[1])
	h, _ := strconv.Atoi(ss[3])
	return Triangle{x: x, y: y, d: ss[2], h: h}
}

func format(o Output) string {
	return fmt.Sprint(o)
}

func solve(a, b Triangle) Output {
	am := makeMap(a)
	bm := makeMap(b)
	ret := 0
	for k, v := range am {
		if bv, ok := bm[k]; ok {
			ret += countOverlap(v, bv)
		}
	}
	return ret
}

func countOverlap(a, b Range) int {
	min := a.min
	if min < b.min {
		min = b.min
	}
	max := a.max
	if max > b.max {
		max = b.max
	}
	if max-min < 0 {
		return 0
	}
	return max - min + 1
}

func makeMap(t Triangle) map[int]Range {
	switch t.d {
	case "T":
		return makeMapTB(t, 1)
	case "B":
		return makeMapTB(t, -1)
	case "R":
		return makeMapLR(t, t.d)
	case "L":
		return makeMapLR(t, t.d)
	default:
		panic("makeMap")
	}
}

func makeMapTB(t Triangle, dir int) map[int]Range {
	hoge := make(map[int]Range)
	for i := 0; i < t.h; i++ {
		hoge[t.y+i*dir] = Range{t.x - i, t.x + i}
	}
	return hoge
}

func makeMapLR(t Triangle, dir string) map[int]Range {
	hoge := make(map[int]Range)
	for i := 0; i < t.h; i++ {
		min := t.x + i
		max := t.x + t.h - 1
		if dir == "R" {
			min = t.x - t.h + 1
			max = t.x - i
		}
		hoge[t.y-i] = Range{min, max}
		hoge[t.y+i] = Range{min, max}
	}
	return hoge
}

main_test.go

package main

import (
	"testing"
)

var table = []struct {
	in, out string
}{
	{"7,0R6/3,1B5", "15"},
	{"1,6L4/4,9R9", "4"},
	{"0,2R4/1,3B4", "3"},
	{"1,2L4/1,2L5", "16"},
	{"3,2L5/5,6B4", "8"},
	{"4,1B3/6,3B4", "4"},
	{"4,4R7/4,3R5", "20"},
	{"4,5R9/1,7T3", "7"},
	{"4,7T9/1,6T3", "1"},
	{"4,8B7/3,7L4", "10"},
	{"5,3L3/9,8L4", "0"},
	{"5,6B4/4,4R2", "3"},
	{"5,6B4/8,5R4", "8"},
	{"5,8B9/5,2L2", "4"},
	{"6,1L5/7,1T2", "3"},
	{"7,2B5/7,2T4", "1"},
	{"7,3T9/9,6L6", "11"},
	{"8,0R6/8,1R7", "30"},
	{"0,4R7/4,6R10", "36"},
	{"10,4L4/9,1T6", "9"},
	{"2,2T7/6,7T10", "4"},
	{"2,7R4/1,6L8", "2"},
	{"3,0R10/1,2T7", "7"},
	{"3,5T2/3,6B10", "2"},
	{"4,7R10/8,2T8", "6"},
	{"6,8B10/4,5B6", "36"},
	{"9,2B7/1,1B10", "6"},
	{"9,3R14/2,4R1", "1"},
	{"3,0R10/0,6B10", "54"},
	{"4,10T8/4,10T8", "64"},
	{"12,11T18/7,18R18", "34"},
	{"46,34T34/34,29T14", "30"},
	{"291,11T120/258,54B130", "424"},
	{"62,170L139/133,172R21", "441"},
	{"98,189B116/183,127R27", "240"},
	{"646,684B96/435,690R772", "0"},
	{"113,668L866/581,859L852", "158404"},
	{"309,321B162/137,420B423", "15750"},
	{"5474,6459R9089/8177,150R5120", "376996"},
	{"2399,1640B2451/1718,2100L1623", "221334"},
	{"5621,8460T7612/2715,5697L8851", "861192"},
}

func TestSolve(t *testing.T) {
	for _, tt := range table {
		s := Solve(tt.in)
		if s != tt.out {
			t.Errorf("Solve(%q) => %q, want %q", tt.in, s, tt.out)
		}
	}
}