Go: package main

import (
	"fmt"
	"math"
)

type Position struct {
	X int64
	Y int64
}

func (one Position) Distance(another Position) int64 {
	return int64(math.Abs(float64(one.X-another.X)) + math.Abs(float64(one.Y-another.Y)))
}

type PersonPosition struct {
	Takayuki Position
	Kazuyuki Position
}

func (one PersonPosition) Distance() int64 {
	return one.Takayuki.Distance(one.Kazuyuki)
}

type Status struct {
	Person PersonPosition
	Turn   int64
}

type PQStatus []*Status

func solve(h, w int64) {
	var tx, ty, kx, ky int64
	fmt.Scan(&tx, &ty, &kx, &ky)
	tx--
	ty--
	kx--
	ky--
	m := make([][]int64, h)
	for i := range m {
		m[i] = make([]int64, w)
		for j := int64(0); j < w; j++ {
			fmt.Scan(&m[i][j])
		}
	}
	start := &Status{Person: PersonPosition{Takayuki: Position{X: tx, Y: ty}, Kazuyuki: Position{X: kx, Y: ky}}, Turn: 0}
	pq := make(PQStatus, 0)
	pq = append(pq, start)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]int64, 0)
	ans := int64(102)
	for len(pq) > 0 {
		now := pq[0]
		pq = pq[1:]
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		if ans <= now.Turn {
			continue
		}

		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = now.Turn

		for i := 0; i < 4; i++ {
			next := &Status{}
			*next = *now
			next.Person.Kazuyuki.X += dx[i]
			next.Person.Kazuyuki.Y += dy[i]
			if next.Person.Kazuyuki.X < 0 || next.Person.Kazuyuki.X >= w ||
				next.Person.Kazuyuki.Y < 0 || next.Person.Kazuyuki.Y >= h ||
				m[next.Person.Kazuyuki.Y][next.Person.Kazuyuki.X] == 1 {
				next.Person.Kazuyuki.X -= dx[i]
				next.Person.Kazuyuki.Y -= dy[i]
			}
			next.Person.Takayuki.X -= dx[i]
			next.Person.Takayuki.Y -= dy[i]
			if next.Person.Takayuki.X < 0 || next.Person.Takayuki.X >= w ||
				next.Person.Takayuki.Y < 0 || next.Person.Takayuki.Y >= h ||
				m[next.Person.Takayuki.Y][next.Person.Takayuki.X] == 1 {
				next.Person.Takayuki.X += dx[i]
				next.Person.Takayuki.Y += dy[i]
			}
			next.Turn++
			if next.Turn <= 100 {
				pq = append(pq, next)
			}
		}
	}
	if ans == 102 {
		fmt.Println("NA")
	} else {
		fmt.Println(ans)
	}
}

func main() {
	var h, w int64
	for {
		fmt.Scan(&h, &w)
		if h == 0 && w == 0 {
			break
		}
		solve(h, w)
	}
}

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

int table[51][51];

bool memo[51][51][51][51];

int main() {

    while(1){

        int w,h;

        //scanf(" %d %d",&w,&h);

        cin >> w >> h;

        if(w==0&&h==0) break;

        int tx,ty,kx,ky;

        //scanf(" %d %d %d %d",&tx,&ty,&kx,&ky);

        cin >> tx >> ty >> kx >> ky;

        tx--;ty--;kx--;ky--;

        for(int i=0;i<51;i++){
            for(int j=0;j<51;j++){
                table[i][j] = 1;
                for(int k=0;k<51;k++){
                    for(int r=0;r<51;r++){
                        memo[i][j][k][r] = false;
                    }
                }
            }
        }

        for(int i=0;i<h;i++){
            for(int j=0;j<w;j++){
                //scanf(" %d",&table[i][j]);
                cin >> table[i][j];
                if(table[i][j] == 1){
                    for(int k=0;k<51;k++){
                        for(int r=0;r<51;r++){
                            memo[i][j][k][r] = true;
                        }
                    }
                }
            }
        }

        /*printf("\n");

        for(int i=0;i<h;i++){
            for(int j=0;j<w;j++){
                printf("%d ",table[i][j]);
            }
            printf("\n");
        }*/

        //memset(memo,false,sizeof(memo));

        queue<vector<int> > q;

        vector<int> v(5);

        v[0] = tx; v[1] = ty; v[2] = kx; v[3] = ky; v[4] = 0;

        if(table[v[0]][v[1]] == 1 || table[v[2]][v[3]] == 1){
            cout << "NA" << endl;
            continue;
        }

        q.push(v);

        bool check = false;

        while(!q.empty()){

            v = q.front(); q.pop();

            if(memo[v[0]][v[1]][v[2]][v[3]]){
                continue;
            }

            if(v[0] == v[2] && v[1] == v[3]){
                check = true;
                cout << v[4] << endl;
                break;
            }

            memo[v[0]][v[1]][v[2]][v[3]] = true;

            v[4]++;

            if(v[4] >= 100){
                break;
            }

            vector<int> before(5);

            for(int i=0;i<5;i++){
                before[i] = v[i];
            }

            v[0]--; v[2]++;

            if(v[0] == -1 || table[v[0]][v[1]] == 1){
                v[0]++;
            }
            if(v[2] == w || table[v[2]][v[3]] == 1){
                v[2]--;
            }

            q.push(v);

            for(int i=0;i<5;i++){
                v[i] = before[i];
            }

            v[0]++; v[2]--;

            if(v[2] == -1 || table[v[2]][v[3]] == 1){
                v[2]++;
            }
            if(v[0] == w || table[v[0]][v[1]] == 1){
                v[0]--;
            }

            q.push(v);


            for(int i=0;i<5;i++){
                v[i] = before[i];
            }

            v[1]++; v[3]--;

            if(v[3] == -1 || table[v[2]][v[3]] == 1){
                v[3]++;
            }
            if(v[1] == h || table[v[0]][v[1]] == 1){
                v[1]--;
            }

            q.push(v);

            for(int i=0;i<5;i++){
                v[i] = before[i];
            }

            v[1]--; v[3]++;

            if(v[1] == -1 || table[v[0]][v[1]] == 1){
                v[1]++;
            }
            if(v[3] == h || table[v[2]][v[3]] == 1){
                v[3]--;
            }

             q.push(v);


            /*if(v[0] >= w || v[1] >= h || v[2] >= w || v[3] >= h || v[0] < 0 || v[1] < 0 || v[2] < 0 || v[3] < 0 || table[v[0]][v[1]] == 1 || table[v[2]][v[3]] == 1){

            }else {
                q.push(v);
            }*/



        }

        if(!check){
            cout << "NA" << endl;
        }



    }

    return 0;
}

C++: // 2011/07/20 Tazoe

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

struct state{
	int tx;
	int ty;
	int kx;
	int ky;
	int tim;
};

int main()
{
	while(true){
		int X, Y;
		cin >> X >> Y;
		if(X==0&&Y==0)
			break;

		int d[52][52];
		for(int y=0; y<=Y+1; y++)
			for(int x=0; x<=X+1; x++)
				d[y][x] = 1;

		struct state now;
		cin >> now.tx >> now.ty;
		cin >> now.kx >> now.ky;
		now.tim = 0;

		queue<struct state> que;
		que.push(now);

		map<int, bool> memo;

		for(int y=1; y<=Y; y++)
			for(int x=1; x<=X; x++)
				cin >> d[y][x];

		while(true){
			if(que.empty()){
				cout << "NA" << endl;
				break;
			}

			now = que.front();
			que.pop();

			int tk = ((now.tx*100+now.ty)*100+now.kx)*100+now.ky;
			if(memo.find(tk)!=memo.end())
				continue;
			else
				memo[tk] = true;

			if(now.tim>=100){
				cout << "NA" << endl;
				break;
			}

			if(now.tx==now.kx&&now.ty==now.ky){
				cout << now.tim << endl;
				break;
			}

			struct state nxt = now;
			if(d[nxt.ty-1][nxt.tx]==0)
				nxt.ty--;
			if(d[nxt.ky+1][nxt.kx]==0)
				nxt.ky++;
			nxt.tim++;
			que.push(nxt);

			nxt = now;
			if(d[nxt.ty+1][nxt.tx]==0)
				nxt.ty++;
			if(d[nxt.ky-1][nxt.kx]==0)
				nxt.ky--;
			nxt.tim++;
			que.push(nxt);

			nxt = now;
			if(d[nxt.ty][nxt.tx-1]==0)
				nxt.tx--;
			if(d[nxt.ky][nxt.kx+1]==0)
				nxt.kx++;
			nxt.tim++;
			que.push(nxt);

			nxt = now;
			if(d[nxt.ty][nxt.tx+1]==0)
				nxt.tx++;
			if(d[nxt.ky][nxt.kx-1]==0)
				nxt.kx--;
			nxt.tim++;
			que.push(nxt);
		}
	}

	return 0;
}