golang 实现广度优先算法(走迷宫)

Posted 2021-02-17 jackluo

maze.go

package main

import (
    "fmt"
    "os"
)

/**
 * 广度优先算法
 */
/**
 * 从文件中读取数据
 */

func readMaze(filename string) [][]int {
    file, err := os.Open(filename)
    if err != nil {
        panic(err)
    }
    var cols, rows int
    fmt.Fscanf(file, "%d %d", &rows, &cols)
    maze := make([][]int, rows)
    for i := range maze {
        maze[i] = make([]int, cols)
        for j := range maze[i] {
            fmt.Fscanf(file, "%d", &maze[i][j])
        }
    }
    return maze
}

/**
 * 定义要走的节点下标
 */
type point struct {
    i, j int
}

/**
 * 定义,四个方向 ,上左下右
 */
var dirs = [4]point{point{-1, 0}, point{0, -1}, point{1, 0}, point{0, 1},}

//走的节点
//走迷宫
/**
 * maze 迷宫地址
 * strt 开始位置
 * end 走出迷宫位置
 */
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] //取一个第一个位置
        Q = Q[1:]
        //fmt.Printf("Q=%v ", Q)
        //发现终点就退出
        if cur == end {
            break
        }

        for _, dir := range dirs { //开始进行 上 左 下 右 的行走路线
            next := cur.add(dir) //拿到下个节点的值
            //撞墙检测
            val, ok := next.at(maze)
            if !ok || val == 1 {
                continue
            }
            //检测是否走过了
            val, ok = next.at(steps)
            if !ok || val != 0 {
                continue
            }
            //检测是否回到原点了不能探索
            if next == start {
                continue
            }
            //开始探索 ,将值存入 steps
            curStep, _ := cur.at(steps)
            steps[next.i][next.j] = curStep + 1

            Q = append(Q, next)
        }
    }
    return steps
}

func (p point) at(grid [][]int) (int, bool) {
    //往上越界,往下越界
    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

}

// 添加节点
func (p point) add(r point) point {
    return point{p.i + r.i, p.j + r.j}
}

func main() {
    maze := readMaze("maze.in") //读取地图数据
    steps := walk(maze, point{0, 0}, point{len(maze) - 1, len(maze[0]) - 1})
    for _, rows := range steps {
        for _, val := range rows {
            fmt.Printf("%3d ", val)
        }
        fmt.Println()
    }

}

 

maze.in

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