7-1 迷宫_算法

7-2 迷宫代码实现

6 5
0 1 0 0 0
0 0 0 1 0
0 1 0 1 0
1 1 1 0 0
0 1 0 0 1
0 1 0 0 0

package main

import (
    "fmt"
    "os"
)

func readMaze(filename string) [][]int {
    file, err := os.Open(filename)
    if err != nil {
        panic(err)
    }

    var row, col int
    fmt.Fscanf(file, "%d %d", &row, &col)

    maze := make([][]int, row)
    for i := range maze {
        maze[i] = make([]int, col)
        for j := range maze[i] {
            fmt.Fscanf(file, "%d", &maze[i][j])
        }
    }

    return maze
}

type point struct {
    i, j int
}

var dirs = [4]point{
    {-1, 0}, {0, -1}, {1, 0}, {0, 1}}

func (p point) add(r point) point {
    return point{p.i + r.i, p.j + r.j}
}

func (p point) at(grid [][]int) (int, bool) {
    if p.i < 0 || p.i >= len(grid) {
        return 0, false
    }

    if p.j < 0 || p.j >= len(grid[p.i]) {
        return 0, false
    }

    return grid[p.i][p.j], true
}

func walk(maze [][]int,
    start, end point) [][]int {
    steps := make([][]int, len(maze))
    for i := range steps {
        steps[i] = make([]int, len(maze[i]))
    }

    Q := []point{start}

    for len(Q) > 0 {
        cur := Q[0]
        Q = Q[1:]

        if cur == end {
            break
        }

        for _, dir := range dirs {
            next := cur.add(dir)

            val, ok := next.at(maze)
            if !ok || val == 1 {
                continue
            }

            val, ok = next.at(steps)
            if !ok || val != 0 {
                continue
            }

            if next == start {
                continue
            }

            curSteps, _ := cur.at(steps)
            steps[next.i][next.j] =
                curSteps + 1

            Q = append(Q, next)
        }
    }

    return steps
}

func main() {
    maze := readMaze("lang/maze/maze.in")

    steps := walk(maze, point{0, 0},
        point{len(maze) - 1, len(maze[0]) - 1})

    for _, row := range steps {
        for _, val := range row {
            fmt.Printf("%3d", val)
        }
        fmt.Println()
    }

    // TODO: construct path from steps
}