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++: #define _USE_MATH_DEFINES
#define INF 10000000
#include <iostream>
#include <sstream>
#include <cmath>
#include <algorithm>
#include <queue>
#include <stack>
#include <limits>
#include <map>
#include <string>
#include <cstring>
#include <set>
#include <deque>
#include <bitset>
#include <list>

using namespace std;

typedef long long ll;
typedef pair <int,int> P;
typedef pair <P,P> PP;
typedef pair <int,PP> PPP;

static const double eps = 1e-8;

static const int moveTo[][2] = {{1,0},{0,-1},{-1,0},{0,1}};
static const int moveToRev[][2] = {{-1,0},{0,1},{1,0},{0,-1}};

int stage[50][50];

int bfs(int tx,int ty,int kx,int ky,int w,int h){
	priority_queue<PPP,vector<PPP>,greater<PPP> > que;
	que.push(PPP(0,PP(P(tx,ty),P(kx,ky))));	

	int res = INF;
	while(!que.empty()){
		int cost = que.top().first;
		if(res <= cost || cost >= 100){
			que.pop(); continue;
		}

		int tx = que.top().second.first.first;
		int ty = que.top().second.first.second;
		int kx = que.top().second.second.first;
		int ky = que.top().second.second.second;

		if(tx==kx && ty == ky) res = min(res,cost);

		que.pop();

		for(int i=0;i<4;i++){
			int tdx = tx + moveTo[i][0];
			int tdy = ty + moveTo[i][1];
			bitset<2> bit;

			if((tdx < 0 || tdx >= w || tdy < 0 || tdy >=h) || stage[tdy][tdx]) {
				tdx = tx;
				tdy = ty;
				bit[0] = 1;
			}

			int kdx = kx + moveToRev[i][0];
			int kdy = ky + moveToRev[i][1];

			if((kdx < 0 || kdx >= w || kdy < 0 || kdy >=h) || stage[kdy][kdx]) {
				kdx = kx;
				kdy = ky;
				bit[1] = 1;
			}
			if(bit == (1<<2) -1) continue;
			que.push(PPP(cost+1,PP(P(tdx,tdy),P(kdx,kdy))));
		}
	}

	return res;
}

int main(){

	int w,h;
	while(~scanf("%d %d",&w,&h)){
		if(w ==h && h==0) break;
		int tx,ty;
		scanf("%d %d",&tx,&ty);
		int kx,ky;
		scanf("%d %d",&kx,&ky);
		for(int y=0;y<h;y++){
			for(int x=0;x<w;x++){
				scanf("%d",&stage[y][x]);
			}
		}

		int res = bfs(tx,ty,kx,ky,w,h);
		if(res == INF) printf("NA\n");
		else printf("%d\n",res);
	}
}

C++: #include<bits/stdc++.h>
#define inf 1<<29
using namespace std;

class State{
public:
  int a,b,c,d;
  State(int a,int b,int c,int d):a(a),b(b),c(c),d(d){};
};

int h,w;
int table[51][51],memo[51][51][51][51];
int Y[4]={-1,0,1,0};
int X[4]={0,1,0,-1};

bool in(int a,int b){
  if(a<0 || b<0 || h<=a || w<=b)return false;
  return true;
}

void init(){
  for(int i=0;i<51;i++)
    for(int j=0;j<51;j++)
      for(int k=0;k<51;k++)
	for(int l=0;l<51;l++)memo[i][j][k][l]=inf;
}

int main()
{
  int a,b,c,d;
  while(1){
    cin>>w>>h;
    if(h+w==0)break;
    cin>>b>>a>>d>>c;
    a--;b--;c--;d--;
    for(int i=0;i<h;i++)for(int j=0;j<w;j++)cin>>table[i][j];
    init();

    queue<State> q;
    q.push(State(a,b,c,d));
    memo[a][b][c][d]=0;

    int ans=inf;
    while(!q.empty()){
      State u=q.front();
      q.pop();
      if(u.a==u.c && u.b==u.d){
	ans=min(memo[u.a][u.b][u.c][u.d],ans);
        break;
      }

      if(memo[u.a][u.b][u.c][u.d]>=100)continue;

      for(int i=0;i<4;i++){
	int A=u.a+Y[i],B=u.b+X[i],C=u.c+Y[(i+2)%4],D=u.d+X[(i+2)%4];
	if(!in(A,B))continue;
	if(!in(C,D))continue;
	if(table[A][B]){
	  A=u.a;
	  B=u.b;
	}
	if(table[C][D]){
	  C=u.c;
	  D=u.d;
	}
	if(memo[A][B][C][D]>memo[u.a][u.b][u.c][u.d]+1){
	  q.push(State(A,B,C,D));
	  memo[A][B][C][D]=memo[u.a][u.b][u.c][u.d]+1;
	}
      }
    }
    if(ans>=100)cout<<"NA"<<endl;
    else cout<<ans<<endl;
  }
  return 0;
}

C++: #include <bits/stdc++.h>
#define PB push_back
#define MP make_pair
#define REP(i,n) for (int i=0;i<(n);i++)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define ALL(a) (a).begin(),(a).end()
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
const int INF=1e9;
const int MOD=100000;
int B=1000000;
int dtx[4]={0,1,0,-1};
int dty[4]={1,0,-1,0};
int dkx[4]={0,-1,0,1};
int dky[4]={-1,0,1,0};
bool fld[50][50];
bool used[50][50][50][50];
struct A{int tx,ty,kx,ky,cnt;};
int X,Y;
bool pos(int x,int y){
      if(x<0||x>=X||y<0||y>=Y)return false;
      if(fld[x][y])return false;
      return true;
}
int main(){
      int tx,ty,kx,ky;
      while(cin>>X>>Y&&(X||Y)){
            int ans=-1;
            memset(used,false,sizeof(used));
            cin>>tx>>ty>>kx>>ky;tx--;ty--;kx--;ky--;
            REP(i,Y)REP(j,X)cin>>fld[j][i];
            queue<A>Q;
            Q.push((A){tx,ty,kx,ky,0});
            while(Q.size()){
                  A a=Q.front();Q.pop();
                  if(a.cnt>100)continue;
                  if(a.tx==a.kx&&a.ty==a.ky){
                        ans=a.cnt;
                        break;
                  }
                  //cout<<a.tx<<" "<<a.ty<<" "<<a.cnt<<" "<<a.kx<<" "<<a.ky<<endl;
                  REP(i,4){
                        int ntx=a.tx+dtx[i],nty=a.ty+dty[i];
                        int nkx=a.kx+dkx[i],nky=a.ky+dky[i];
                        if(!pos(ntx,nty)||!pos(nkx,nky)||used[ntx][nty][nkx][nky])continue;
                        used[ntx][nty][nkx][nky]=true;
                        Q.push((A){ntx,nty,nkx,nky,a.cnt+1});
                  }
            }
            if(ans==-1)cout<<"NA"<<endl;
            else cout<<ans<<endl;
      }
}