Go: package main

import (
	"bufio"
	"container/list"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func main() {
	io := NewIo()
	defer io.Flush()
	for {
		w, h := io.NextInt(), io.NextInt()
		if w == 0 {
			break
		}
		xWall := make([][]int, h)
		yWall := make([][]int, h)
		for i := 0; i < h; i++ {
			xWall[i], yWall[i] = make([]int, w), make([]int, w)
			for j := 0; j < w; j++ {
				xWall[i][j], yWall[i][j] = -1, -1
			}
		}
		for i := 0; i < h*2-1; i++ {
			if i%2 == 0 {
				for j := 0; j < w-1; j++ {
					xWall[i/2][j] = io.NextInt()
				}
			} else {
				for j := 0; j < w; j++ {
					yWall[i/2][j] = io.NextInt()
				}
			}
		}
		//io.Println(bfs(w, h, xWall, yWall))
		fmt.Println(bfs(w, h, xWall, yWall))
	}
}

type P struct {
	x, y int
}

func bfs(w, h int, x, y [][]int) int {
	d := make([][]int, h)
	for i := 0; i < h; i++ {
		d[i] = make([]int, w)
	}
	q := list.New()
	q.PushBack(P{0, 0})
	d[0][0] = 1

	for q.Len() != 0 {
		pos := q.Remove(q.Front()).(P)
		if pos.x == w-1 && pos.y == h-1 {
			break
		}
		if pos.x > 0 && x[pos.y][pos.x-1] == 0 && d[pos.y][pos.x-1] == 0 {
			d[pos.y][pos.x-1] = d[pos.y][pos.x] + 1
			q.PushBack(P{pos.x - 1, pos.y})
		}
		if pos.x < w-1 && x[pos.y][pos.x] == 0 && d[pos.y][pos.x+1] == 0 {
			d[pos.y][pos.x+1] = d[pos.y][pos.x] + 1
			q.PushBack(P{pos.x + 1, pos.y})
		}
		if pos.y > 0 && y[pos.y-1][pos.x] == 0 && d[pos.y-1][pos.x] == 0 {
			d[pos.y-1][pos.x] = d[pos.y][pos.x] + 1
			q.PushBack(P{pos.x, pos.y - 1})
		}
		if pos.y < h-1 && y[pos.y][pos.x] == 0 && d[pos.y+1][pos.x] == 0 {
			d[pos.y+1][pos.x] = d[pos.y][pos.x] + 1
			q.PushBack(P{pos.x, pos.y + 1})
		}
	}
	return d[h-1][w-1]
}

// I/O template
type Io struct {
	reader    *bufio.Reader
	writer    *bufio.Writer
	tokens    []string
	nextToken int
}

func NewIo() *Io {
	return &Io{
		reader: bufio.NewReader(os.Stdin),
		writer: bufio.NewWriter(os.Stdout),
	}
}

func (io *Io) Flush() {
	err := io.writer.Flush()
	if err != nil {
		panic(err)
	}
}

func (io *Io) NextLine() string {
	var buff []byte
	for {
		line, isPrefix, err := io.reader.ReadLine()
		if err != nil {
			panic(err)
		}
		buff = append(buff, line...)
		if !isPrefix {
			break
		}
	}
	return string(buff)
}

func (io *Io) Next() string {
	for io.nextToken >= len(io.tokens) {
		line := io.NextLine()
		io.tokens = strings.Fields(line)
		io.nextToken = 0
	}
	s := io.tokens[io.nextToken]
	io.nextToken++
	return s
}

func (io *Io) NextInt() int {
	i, err := strconv.Atoi(io.Next())
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) NextFloat() float64 {
	i, err := strconv.ParseFloat(io.Next(), 64)
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) Println(a ...interface{}) {
	fmt.Fprintln(io.writer, a...)
}

func (io *Io) Printf(format string, a ...interface{}) {
	fmt.Fprintf(io.writer, format, a...)
}

func (io *Io) PrintIntSlice(a []int) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func (io *Io) PrintStringSlice(a []string) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func Log(name string, value interface{}) {
	fmt.Fprintf(os.Stderr, "%s=%+v\n", name, value)
}

func ExampleIo() {
	io := NewIo()
	defer io.Flush()
	a := make([]int, 0, 3)
	a[0], a[1], a[2] = io.NextInt(), io.NextInt(), io.NextInt()
	io.Println(a)
	io.PrintIntSlice(a)
	Log("io", a)
}

C++: #include <vector>
#include <list>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <deque>
#include <algorithm>
#include <utility>
#include <functional>
#include <sstream>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <climits>
#include <cassert>
using namespace std;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define EXIST(s, e) ((s).find(e)!=(s).end())
#define FOR(i,a,b) for(int i=(a); i<(b); ++i)
#define REP(i,n) FOR(i, 0, n)

typedef vector<vvi> vvvi;
typedef vector<vvvi> vvvvi;

int main() {
	int W, H;
	while (cin >> W >> H, W || H) {
		vvi visited = vvi(H, vi(W, false));
		vvvvi wall = vvvvi(H, vvvi(W, vvi(H, vi(W, false))));
		REP(i, H) {
			REP(j, W-1) {
				bool b; cin >> b;
				if (b) {
					wall[i][j][i][j+1] = true;
					wall[i][j+1][i][j] = true;
				}
			}
			if (i == H-1) break;
			REP(j, W) {
				bool b; cin >> b;
				if (b) {
					wall[i][j][i+1][j] = true;
					wall[i+1][j][i][j] = true;
				}
			}
		}

		REP(i,H){
			REP(j,W){
				REP(d,4){
			int dy[] = {-1, 0, 1, 0}, dx[] = {0, 1, 0, -1};
					int y=i+dy[d];
					int x=j+dx[d];
					if(y>=0&&x>=0&&y<H&&x<W){
						cerr<<wall[i][j][y][x];
					}else{
						cerr<<"-";
					}
				}
				cout<<" ";
			}
			cout<<endl;
		}

		int ans = 0;
		// < y, x >, steps
		queue<pair<pii, int> > q;
		q.push(make_pair(pii(0, 0), 1));
		while(!q.empty()) {
			pair<pii, int> t = q.front(); q.pop();
			int y = t.first.first, x = t.first.second;
			int cost = t.second;

			if(visited[y][x]) continue;
			visited[y][x] = true;

			// fprintf(stderr, "visiting (%d, %d)\n", y, x);
			// Goal
			if (y == H-1 && x == W-1) {
				// cerr << "Goal" << endl;
				ans = cost;
				break;
			}

			int dy[] = {-1, 0, 1, 0}, dx[] = {0, 1, 0, -1};
			REP(d, 4) {
				int ny = y + dy[d], nx = x + dx[d];
				if ( !((0 <= ny && ny < H) && (0 <= nx && nx < W)) ) {
					continue;
				}
				if ( wall[y][x][ny][nx] ) continue;

				q.push(make_pair(pii(ny, nx), cost + 1));
			}
		}

		cout << ans << endl;
	}
}

C++: #include<bits/stdc++.h>
using namespace std;
int x[900][900],h,w,a,y[900],s,i,j;
queue<int>Q,R;
int main(){
while(true){
memset(x,0,sizeof(x));
memset(y,0,3600);
cin>>w>>h;
if(!w){break;}
for(i=0;i<h*2-1;i++){
if(i%2==1){
for(j=0;j<w;j++){
cin>>a;
if(!a){
x[(i/2)*30+j][(i/2+1)*30+j]=1;
}
}
}
else{
for(j=0;j<w-1;j++){
cin>>a;
if(a==0){
x[(i/2)*30+j][(i/2)*30+j+1]=1;
}
}
}
}
Q.push(0);
s=1;
y[0]=1;
while(y[(h-1)*30+(w-1)]==0){
while(!Q.empty()){
a=Q.front();
for(int j=0;j<900;j++){
if((x[a][j]||x[j][a])&&!y[j]){
y[j]=1;
R.push(j);
}
}
Q.pop();
}
while(!R.empty()){
Q.push(R.front());
R.pop();
}
s++;
if(s>999){s=0;break;}
}
while(!Q.empty()){
Q.pop();
}
cout<<s<<endl;
}
}