main.go

package main

import "fmt"

var LARGE = 100000

var p = [][]string{
	[]string{"S", "#", "#", "#"},
	[]string{".", ".", ".", "#"},
	[]string{"#", ".", ".", "."},
	[]string{".", ".", "#", "E"},
	[]string{"#", ".", ".", "."},
}
var sx, sy int = 0, 0
var gx, gy int = 0, 0
var lx, ly = len(p), len(p[0])

type vector struct {
	x int
	y int
}

/* If it is wall, return false */
func updateMap(q [][]int, x, y, r int) bool {
	if x >= 0 && y >= 0 && x < lx && y < ly && (p[x][y] == "." || p[x][y] == "E") {
		if q[x][y] > r+1 {
			q[x][y] = r + 1
			return true
		}
	}
	return false
}

func solve(q [][]int) {
	type Vectors []vector
	var queue Vectors

	queue = append(queue, vector{sx, sy})
	for len(queue) > 0 {
		/* pop from queue */
		v := queue[0]
		queue = queue[1:]
		/* pop end */
		if updateMap(q, v.x+1, v.y, q[v.x][v.y]) {
			queue = append(queue, vector{v.x + 1, v.y})
		}
		if updateMap(q, v.x, v.y+1, q[v.x][v.y]) {
			queue = append(queue, vector{v.x, v.y + 1})
		}
		if updateMap(q, v.x-1, v.y, q[v.x][v.y]) {
			queue = append(queue, vector{v.x - 1, v.y})
		}
		if updateMap(q, v.x, v.y-1, q[v.x][v.y]) {
			queue = append(queue, vector{v.x, v.y - 1})
		}

	}
}

func main() {
	q := make([][]int, len(p))
	for i := range q {
		q[i] = make([]int, len(p[0]))
		for j := range q[i] {
			q[i][j] = LARGE
			if p[i][j] == "S" {
				q[i][j] = 0
				sx, sy = i, j
			}
			if p[i][j] == "E" {
				gx, gy = i, j
			}
		}
	}
	solve(q)
	for _, v1 := range q {
		for _, v2 := range v1 {
			if LARGE == v2 {
				fmt.Printf("#")
			} else {
				fmt.Printf("%d", v2)
			}
		}
		fmt.Println()
	}
}