90 lines
1.5 KiB
Go
90 lines
1.5 KiB
Go
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package part1
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import (
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"bufio"
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"strings"
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)
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var Tiles = map[byte][2][2]int{
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'|': {{0,-1}, {0,1}},
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'-': {{-1,0}, {1,0}},
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'L': {{0,-1}, {1,0}},
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'J': {{0,-1}, {-1,0}},
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'7': {{0,1}, {-1,0}},
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'F': {{0,1}, {1,0}},
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}
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func ReadMap(scanner *bufio.Scanner) (res []string) {
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for scanner.Scan() {
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res = append(res, scanner.Text())
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}
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return
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}
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func FindStart(pipeMap []string) (x,y int) {
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for y = range pipeMap {
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if x = strings.IndexRune(pipeMap[y], 'S'); x > -1 {
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return
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}
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}
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return -1, -1
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}
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func FindFirst(pipeMap []string, sx,sy int) (int, int, int) {
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for y := sy-1; y <= sy+1;y++ {
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if y < 0 || y >= len(pipeMap) {
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continue
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}
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for x := sx-1; x <= sx+1 ;x++ {
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if x < 0 || x >= len(pipeMap[y]) {
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continue
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}
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side, ok := GetSide(pipeMap, sx,sy, x,y)
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if ok {
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return side,x,y
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}
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}
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}
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return -1, -1, -1
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}
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func GetSide(pipeMap []string, px,py, x,y int) ( int, bool ) {
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tile := pipeMap[y][x]
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dirs, ok := Tiles[tile]
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if !ok {
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return -1, false
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}
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for i,dir := range dirs {
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if x + dir[0] == px && y + dir[1] == py {
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return i, true
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}
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}
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return -1, false
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}
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func FindNext(pipeMap []string, side, x,y int) (int,int,int) {
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tile := pipeMap[y][x]
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dir := Tiles[tile][1-side]
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nx,ny := x+dir[0], y+dir[1]
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nside, _ := GetSide(pipeMap, x,y, nx,ny)
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return nside,nx,ny
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}
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func LoopSize(pipeMap []string) int {
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x,y := FindStart(pipeMap)
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side,x,y := FindFirst(pipeMap, x,y)
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count := 1
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for pipeMap[y][x] != 'S' {
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count++
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side,x,y = FindNext(pipeMap, side, x,y)
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}
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return count
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}
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