143 lines
4.3 KiB
Go
143 lines
4.3 KiB
Go
package common
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import (
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"bufio"
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"math"
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)
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type Tile struct {
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height int
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steps int
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}
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func NewTile(height int) *Tile {
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return &Tile{height, math.MaxInt32}
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}
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func (tile Tile) GetSteps() int {
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return tile.steps
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}
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type Map struct {
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tiles [][]Tile
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start *Tile
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end *Tile
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}
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func (heightmap Map) GetEndTile() Tile {
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return *heightmap.end
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}
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func (heightmap Map) GetStartTile() Tile {
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return *heightmap.start
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}
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func (heightmap Map) FindBestStart() Tile {
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min := math.MaxInt32
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var bestStart Tile
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for i := 0; i < len(heightmap.tiles); i++ {
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for j := 0; j < len(heightmap.tiles[i]); j++ {
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if heightmap.tiles[i][j].height == 1 && heightmap.tiles[i][j].steps < min {
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bestStart = heightmap.tiles[i][j]
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min = bestStart.steps
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}
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}
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}
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return bestStart
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}
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func (heightmap *Map) ComputeStepsFromStart() {
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heightmap.start.steps = 0
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for i := 0; i < len(heightmap.tiles); i++ {
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for j := 0; j < len(heightmap.tiles[i]); j++ {
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if &heightmap.tiles[i][j] == heightmap.start {
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heightmap.ComputeSteps(i, j, 1)
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}
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}
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}
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}
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func (heightmap *Map) ComputeStepsFromEnd() {
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heightmap.end.steps = 0
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for i := 0; i < len(heightmap.tiles); i++ {
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for j := 0; j < len(heightmap.tiles[i]); j++ {
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if &heightmap.tiles[i][j] == heightmap.end {
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heightmap.ComputeStepsInReverse(i, j, 1)
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}
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}
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}
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}
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func (heightmap *Map) ComputeSteps(row int, column int, steps int) {
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if row > 0 && heightmap.tiles[row-1][column].steps > steps &&
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heightmap.tiles[row-1][column].height <= heightmap.tiles[row][column].height + 1 {
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heightmap.tiles[row-1][column].steps = steps
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heightmap.ComputeSteps(row-1, column, steps+1)
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}
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if row < len(heightmap.tiles)-1 && heightmap.tiles[row+1][column].steps > steps &&
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heightmap.tiles[row+1][column].height <= heightmap.tiles[row][column].height + 1 {
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heightmap.tiles[row+1][column].steps = steps
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heightmap.ComputeSteps(row+1, column, steps+1)
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}
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if column > 0 && heightmap.tiles[row][column-1].steps > steps &&
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heightmap.tiles[row][column-1].height <= heightmap.tiles[row][column].height + 1 {
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heightmap.tiles[row][column-1].steps = steps
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heightmap.ComputeSteps(row, column-1, steps+1)
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}
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if column < len(heightmap.tiles[0])-1 && heightmap.tiles[row][column+1].steps > steps &&
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heightmap.tiles[row][column+1].height <= heightmap.tiles[row][column].height + 1 {
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heightmap.tiles[row][column+1].steps = steps
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heightmap.ComputeSteps(row, column+1, steps+1)
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}
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}
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func (heightmap *Map) ComputeStepsInReverse(row int, column int, steps int) {
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if row > 0 && heightmap.tiles[row-1][column].steps > steps &&
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heightmap.tiles[row-1][column].height + 1 >= heightmap.tiles[row][column].height {
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heightmap.tiles[row-1][column].steps = steps
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heightmap.ComputeStepsInReverse(row-1, column, steps+1)
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}
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if row < len(heightmap.tiles)-1 && heightmap.tiles[row+1][column].steps > steps &&
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heightmap.tiles[row+1][column].height + 1 >= heightmap.tiles[row][column].height {
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heightmap.tiles[row+1][column].steps = steps
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heightmap.ComputeStepsInReverse(row+1, column, steps+1)
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}
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if column > 0 && heightmap.tiles[row][column-1].steps > steps &&
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heightmap.tiles[row][column-1].height + 1 >= heightmap.tiles[row][column].height {
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heightmap.tiles[row][column-1].steps = steps
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heightmap.ComputeStepsInReverse(row, column-1, steps+1)
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}
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if column < len(heightmap.tiles[0])-1 && heightmap.tiles[row][column+1].steps > steps &&
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heightmap.tiles[row][column+1].height + 1 >= heightmap.tiles[row][column].height {
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heightmap.tiles[row][column+1].steps = steps
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heightmap.ComputeStepsInReverse(row, column+1, steps+1)
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}
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}
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func Parse(scanner bufio.Scanner) Map {
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heightmap := Map{}
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for scanner.Scan() {
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line := scanner.Text()
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heightmapRow := make([]Tile, len(line))
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for i := 0; i < len(line); i++ {
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if line[i] == 'S' {
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heightmapRow[i] = *NewTile(1)
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heightmap.start = &heightmapRow[i]
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} else if line[i] == 'E' {
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heightmapRow[i] = *NewTile(26)
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heightmap.end = &heightmapRow[i]
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} else {
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heightmapRow[i] = *NewTile(int(line[i] - 'a' + 1))
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}
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}
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heightmap.tiles = append(heightmap.tiles, heightmapRow)
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}
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return heightmap
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}
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