Go: package main

import (
	"container/heap"
	"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 (pq PQStatus) Len() int {
	return len(pq)
}
func (pq PQStatus) Less(i, j int) bool {
	if pq[i].Turn == pq[j].Turn {
		return pq[i].Person.Distance() < pq[j].Person.Distance()
	}
	return pq[i].Turn < pq[j].Turn
}

func (pq PQStatus) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
}

func (pq *PQStatus) Push(x interface{}) {
	item := x.(*Status)
	*pq = append(*pq, item)
}

func (pq *PQStatus) Pop() interface{} {
	old := *pq
	n := len(old)
	item := old[n-1]
	*pq = old[0 : n-1]
	return item
}

func solve(h, w int64) {
	var tx, ty, kx, ky int64
	fmt.Scan(&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)
	heap.Init(&pq)
	heap.Push(&pq, start)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]struct{}, 0)
	for pq.Len() > 0 {
		now := heap.Pop(&pq).(*Status)
		if now.Person.Distance() == 0 {
			fmt.Println(now.Turn)
			return
		}
		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = struct{}{}
		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 += 1
			if next.Turn < 100 {
				heap.Push(&pq, next)
			}
		}
	}
	fmt.Println("NA")
}

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

C++: #include<cstdio>
#include<iostream>
#include<vector>
#include<algorithm>
#include<map>
#include<set>
#include<queue>
#include<string>
 
using namespace std;
 
#define rep(i,n) for(int i=0;i<int(n);i++)
#define reps(i,n) for(int i=1;i<=int(n);i++)
#define sint(i) scanf("%d",&i);
#define sintt(i,j) scanf("%d%d",&i,&j);
#define sinttt(i,j,k) scanf("%d%d%d",&i,&j,&k);
#define sintttt(i,j,k,m) scanf("%d%d%d%d",&i,&j,&k,&m);
 
#define INF 1010000000
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
 
class S{
    public:
    int a,b,c,d;
    int n;
    S(int p,int n,int t,int k,int i):a(p),b(n),c(t),d(k),n(i){}
     
};
 
char visit[51][51][51][51];
 
int main(){
    while(1){
        int n,m;
        sintt(n,m);
        if(n==0)break;
        int a,b,c,d;
        sintttt(a,b,c,d);
         
        int masu[51][51];
         
        rep(i,51)rep(j,51)masu[j][i]=0;
        reps(i,m){
            reps(j,n){
                sint(masu[j][i]);
            }
        }
         
        queue<S> que;
        que.push(S(a,b,c,d,0));
        rep(i,51)rep(j,51)rep(k,51)rep(p,51)visit[i][j][k][p]=0;
        int ans=0;
        while(1){
            if(que.empty()==1){
                break;
            }
             
             
            S u=que.front();
            que.pop();
             
            //printf("%d %d  %d %d  %d\n",u.a,u.b,u.c,u.d,u.n);
             
            if(visit[u.a][u.b][u.c][u.d]==1){
                continue;
            }
            visit[u.a][u.b][u.c][u.d]=1;
             
            if(u.a==u.c && u.b==u.d){
                ans=u.n;
                break;
            }
             
            rep(i,4){
                int dx1=u.a+dx[i];
                int dy1=u.b+dy[i];
                 
                int dx2=u.c+dx[i]*-1;
                int dy2=u.d+dy[i]*-1;
                 
                //printf("push %d %d %d %d\n",dx1,dy1,dx2,dy2);
                 
                if(dx1<=0 || dy1<=0 || dx1>n ||dy1>m|| masu[dx1][dy1]==1){
                    dx1-=dx[i];
                    dy1-=dy[i];
                }
                if(dx2<=0 || dy2<=0 || dx2>n ||dy2>m|| masu[dx2][dy2]==1){
                    dx2-=dx[i]*-1;
                    dy2-=dy[i]*-1;
                }
                 
                //printf("push %d %d %d %d\n",dx1,dy1,dx2,dy2);
                que.push(S(dx1,dy1,dx2,dy2,u.n+1));
            }
        }
        if(ans==0){
            puts("NA");
        }else{
            printf("%d\n",ans);
        }
    }
}

C++: #include<iostream>
#include<queue>
#include<map>
using namespace std;
int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };
class state {
public:
	int tx;
	int ty;
	int kx;
	int ky;
	bool operator < (const state &s)const {
		if (ty != s.ty)return ty < s.ty;
		if (tx != s.tx)return tx < s.tx;
		if (ky != s.ky)return ky < s.ky;
		if (kx != s.kx)return kx < s.kx;
		return false;
	}
};
int main() {
	while (true) {
		int W, H;
		cin >> W >> H;
		if (W == 0 && H == 0)
			break;
		int d[52][52];
		for (int i = 0; i < H + 2; i++) {
			for (int j = 0; j < W + 2; j++) {
				d[i][j] = 1;
			}
		}
		state num;
		cin >> num.tx >> num.ty >> num.kx >> num.ky;
		for (int i = 1; i < H + 1; i++) {
			for (int j = 1; j < W + 1; j++) {
				cin >> d[i][j];
			}
		}
		queue<state> q;
		q.push(num);
		map<state, int> m;
		m[num] = 0;
		while (true) {
			num = q.front();
			q.pop();
			if (m[num] >= 100) {
				cout << "NA" << endl;
				break;
			}
			if (num.tx == num.kx && num.ty == num.ky) {
				cout << m[num] << endl;
				break;
			}
			for (int i = 0; i < 4; i++) {
				state copy = num;
				if (d[copy.ty + dy[i]][copy.tx + dx[i]] == 0) {
					copy.ty += dy[i];
					copy.tx += dx[i];
				}
				if (d[copy.ky - dy[i]][copy.kx - dx[i]] == 0) {
					copy.ky -= dy[i];
					copy.kx -= dx[i];
				}
				if (m.find(copy)==m.end()) {
					q.push(copy);
					m[copy] = m[num]+1;
				}
			}
			if (q.empty()) {
				cout << "NA" << endl;
				break;
			}
		}
		m.clear();
		while (!q.empty()) {
			q.pop();
		}
	}
	return 0;
}