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 <bits/stdc++.h>
using namespace std;
using P = pair<int, int>;

const int dx[] = { -1, 0, 1, 0 };
const int dy[] = { 0, -1, 0, 1 };

int main()
{
	int h, w, b;
	while(cin >> w >> h, w | h){
		vector<vector<int>> G(h * w);
		for(int i = 0;i < h * 2 - 1;i++){
			if(i & 1){
				for(int j = 0;j < w;j++){
					cin >> b;
					if(b == 0){
						G[(i / 2 + 1) * w + j].push_back(i / 2 * w + j);
						G[i / 2 * w + j].push_back((i / 2 + 1) * w + j);
					}
				}
			}
			else{
				for(int j = 1;j < w;j++){
					cin >> b;
					if(b == 0){
						G[i / 2 * w + j - 1].push_back(i / 2 * w + j);
						G[i / 2 * w + j].push_back(i / 2 * w + j - 1);
					}
				}
			}
		}
		vector<int> res(h * w, -1);
		queue<P> q;
		q.push(P(0, 1));
		res[0] = 1;
		while(!q.empty()){
			auto p = q.front(); q.pop();
			for(auto to : G[p.first]){
				if(res[to] == -1){
					q.push(P(to, p.second + 1));
					res[to] = p.second + 1;
				}
			}
			if(res[h * w - 1] != -1){
				break;
			}
		}
		cout << (res[h * w - 1] == -1 ? 0 : res[h * w - 1]) << endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
#define all(a) (a).begin(),(a).end()
#define rep(i,n) for(int i=0;i<(n);i++)
using namespace std;
typedef pair <int,int> pii;
#define FST first
#define SEC second
#define WMAX 59
#define HMAX 59

int dd[5]={0,1,0,-1,0};
int w,h;

void print(int map[WMAX][HMAX]){
  rep(i,h){
    rep(j,w){
      printf("%d",map[j][i]);
    }
    putchar('\n');
  }
}

int dfs_aux(int map[WMAX][HMAX],int sx,int sy,int *min,int count){
  if(count<*min)
    rep(i,4){
      if(count>=*min)
	break;
      int nx=sx+dd[i],ny=sy+dd[i+1];
      if(nx<0 || w<=nx || ny<0 || h<=ny || map[nx][ny])
	continue;

      if(nx==w-1 && ny==h-1 && count<*min){
	*min=count;
	continue;
      }
    
      map[sx][sy]=1;
      dfs_aux(map,nx,ny,min,count+1);
      if(count<*min)
	break;
      map[sx][sy]=0;
    }
}

bool goal(int map[WMAX][HMAX]){
  stack <pii> s;
  s.push(pii(w-1,h-1));
  while(!s.empty()){
    int cx=s.top().FST, cy=s.top().SEC;
    s.pop();
    if(map[cx][cy]==0)
      map[cx][cy]=1;
    rep(r,4){
      int nx=cx+dd[r], ny=cy+dd[r+1];
      if(nx<0||w<=nx||ny<0||h<=ny||map[nx][ny])
	continue;
      s.push(pii(nx,ny));
    }
  }
  //print(map);
  if(map[0][0])
    return true;
  return false;
}

int dfs(int map[WMAX][HMAX]){
  int copy[WMAX][HMAX];
  rep(i,h){
    rep(j,w){
      copy[j][i]=map[j][i];
    }
  }
  if(!goal(copy))
    return 0;

  int min=INT_MAX;
  dfs_aux(map,0,0,&min,0);
  return (min+3)/2;
}

void init_map(int map[WMAX][HMAX]){
  rep(i,2*h-1){
    rep(j,2*w-1){
      map[j][i]=0;
    }
  }
}

int main(){
  int map[WMAX][HMAX];
  for(;;){
    scanf("%d%d",&w,&h);
    if(!(w+h)) break;
    init_map(map);
    rep(i,h){
      rep(j,w-1){
	scanf("%d",&map[2*j+1][2*i]);
	if(map[2*j+1][2*i])
	  map[2*j+1][2*i-1] = map[2*j+1][2*i+1] = 1;
      }
      if(i==h-1)break;
      rep(j,w){
	int m;
	scanf("%d",&map[2*j][2*i+1]);
	if(map[2*j][2*i+1])
	  map[2*j+1][2*i+1]= map[2*j-1][2*i+1] = 1;
      }
    }
    w=2*w-1;
    h=2*h-1;
    //print(map);
    cout << dfs(map) << endl;
  }
}

C++: #include<iostream>
#include<algorithm>
#include<queue>
using namespace std;
const int dy[] = { 0, 2, 0, -2 };
const int dx[] = { 2, 0, -2, 0 };
static int w;
static int h;
static int map[100][100];
int main()
{
	while (cin >> w >> h && w != 0 || h != 0)
	{
		for (int i = 0; i < 100; i++)
		{
			for (int j = 0; j < 100; j++)
			{
				map[i][j] = 0;
			}
		}

		for (int i = 0; i < h + (h - 1); i++)
		{
			for (int j = (i + 1) % 2; j < w + (w - (i + 1) % 2); j+=2)
			{
				cin >> map[i][j];
			}
		}
		int ans = 0;
		bool path[100][100];
		for (int i = 0; i < h + (h - 1); i++)
		{
			for (int j = 0; j < w + (w - 1); j++)
			{
				path[i][j] = false;
			}
		}
		queue<pair<pair<int,int>,int> >q;
		q.push(make_pair(make_pair(0, 0), 1));
		while (q.size() > 0)
		{
			pair<pair<int,int>,int> p = q.front();
			q.pop();
			path[p.first.second][p.first.first] = true;
			if (p.first.first == w + (w - 1) - 1 && p.first.second == h + (h - 1) - 1)
			{
				ans = p.second;
				break;
			}
			for (int i = 0; i < 4; i++)
			{
				int nx = p.first.first + dx[i];
				int ny = p.first.second + dy[i];
				if (nx < 0 || nx >= w + (w - 1))continue;
				if (ny < 0 || ny >= h + (h - 1))continue;
				if (map[ny][nx] == 1)continue;
				if (path[ny][nx])continue;
				if (map[p.first.second + (dy[i] / 2)][p.first.first + (dx[i] / 2)] == 1)continue;
				q.push(make_pair(make_pair(nx,ny),p.second + 1));
			}
		}

		cout << ans << endl;


	}
	return 0;
}