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 <iostream>
#include <queue>
using namespace std;

struct pos{
	int x;
	int y;
	int dis;
};

int main(){
	int w, h;
	while(cin >> w >> h){
		if(w == 0 || h == 0) break;
		int map[65][65];
		for(int i = 0; i < 65; i++){
			for(int j = 0; j < 65; j++){
				map[j][i] = 1;
			}
		}

		for(int i = 1; i <= h; i++){
			for(int j = 1; j <= w; j++){
				map[i*2-1][j*2-1] = 0;
			}
		}

		int l = 1;
		for(int i = 1; i <= h*2-1; i++){
			if(i % 2 == 1){	
				for(int j = 1; j <= w-1; j++){
					int input;
					cin >> input;
					map[l*2-1][j*2] = input;
				}
			}else{
				for(int j = 1; j <= w; j++){
					int input;
					cin >> input;
					map[l*2][j*2-1] = input;
				}
				l++;
			}
		}

		queue<pos> q;
		map[1][1] = 1;
		pos p;
		p.x = 1;
		p.y = 1;
		p.dis = 1;
		q.push(p);
		int x1[] = {-1, 0, 1, 0}, y1[] = {0, -1, 0, 1};
		while(!q.empty()){
			p = q.front();
			q.pop();
			for(int i = 0; i < 4; i++){
				pos p1 = p;
				p1.x += x1[i]; p1.y += y1[i];
				if(!map[p1.x][p1.y]){
					p1.dis++;
					map[p1.x][p1.y] = p1.dis;
					q.push(p1);
				}
 			}
		}

		int ans = (map[h*2-1][w*2-1] + 1) /2;

		for(int i = 0; i <= h*2; i++){
			for(int j = 0; j <= w*2; j++){
				cout << map[i][j] << " ";
			}
			cout << endl;
		}

		cout << ans << endl;

	}

	return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <string>
#include <stack>
#include <queue>
#include <cmath>
#include <cstdio>
#include <istream>
#include <sstream>
#include <iomanip>
using namespace std;

typedef ostringstream oss;
typedef istringstream iss;

typedef vector<int> vi;
typedef vector< vi > vvi;

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

void dfs(vector< vvi >& gred, int h, int w) {
	for (int i = 0; i < 4; i++) {
		if (!gred[h][w][i]) {
			int deh = h + dy[i];
			int dew = w + dx[i];
			if (gred[deh][dew][4] > gred[h][w][4] + 1 || (gred[deh][dew][4] == 1 && !(deh == 0 && dew == 0))) {
				gred[deh][dew][4] = gred[h][w][4] + 1;
				dfs(gred, deh, dew);
			}
		}
	}
}

int main(void) {
	int W, H;
	while (cin >> W >> H, W) {
		vector< vvi > gred(H, vvi(W, vi(5, 1) ) );

		for (int h = 0; h < H * 2 - 1; h++) {
			int tmp;
			if (!(h % 2)) for(int w = 0; w < W - 1; w++) {	//縦
				cin >> tmp;
				gred[h / 2][w][1] = tmp;
				gred[h / 2][w + 1][3] = tmp;
			}else for(int w = 0; w < W; w++) {		//横
				cin >> tmp;
				gred[h / 2][w][2] = tmp;
				gred[h / 2 + 1][w][0] = tmp;
			}
		}

		dfs(gred, 0, 0);

		int res = gred[H - 1][W - 1][4];
		cout << (res == 1 ? 0 : res) << endl;
	}

	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

const int dh[4] = {1, -1, 0, 0};
const int dw[4] = {0, 0, 1, -1};

int main(){
    while(1){
        int H, W;
        cin >> W >> H;
        if(W == 0 && H == 0) break;
        vector<vector<int>> block_h(H);
        vector<vector<int>> block_w(H-1);
        for(int i = 0; i < 2*H-1; i++){
            if(i % 2 == 0){
                for(int j = 0; j < W - 1; j++){
                    int p;
                    cin >> p;
                    block_h[i/2].push_back(p);
                }
            }
            else{
                for(int j = 0; j < W; j++){
                    int p;
                    cin >> p;
                    block_w[i/2].push_back(p);
                }
            }
        }

        vector<vector<int>> dist(H, vector<int>(W, -1));
        dist[0][0] = 1;

        queue<pair<int, int>> que;
        que.push(make_pair(0, 0));

        while(!que.empty()){
            pair<int, int> current_pos = que.front();
            int h = current_pos.first;
            int w = current_pos.second;
            que.pop();

            for(int d = 0; d < 4; d++){
                int next_h = h + dh[d];
                int next_w = w + dw[d];
                if(next_h < 0 || next_h >= H || next_w < 0 || next_w >= W) continue;
                if(d == 0 && block_w[h][next_w] == 1) continue;
                if(d == 1 && block_w[next_h][next_w] == 1) continue;
                if(d == 2 && block_h[next_h][w] == 1) continue;
                if(d == 3 && block_h[next_h][next_w] == 1) continue;

                if(dist[next_h][next_w] == -1){
                    dist[next_h][next_w] = dist[h][w] + 1;
                    que.push(make_pair(next_h, next_w));
                }
            }
        }
        if(dist[H-1][W-1] == -1) cout << 0 << endl;
        else cout << dist[H-1][W-1] << endl;
    }
}