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 (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)
	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)
	//pq.Push(start)
	pq = append(pq, start)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]int64, 0)
	ans := int64(101)
	for pq.Len() > 0 {
		//now := heap.Pop(&pq).(*Status)
		//now := pq.Pop().(*Status)
		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 += 1
			if next.Turn <= 100 {
				//heap.Push(&pq, next)
				//pq.Push(next)
				pq = append(pq, next)
			}
		}
	}
	if ans == 101 {
		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 <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstring>
#include <sstream>
#include <cassert>
#include <list>
using namespace std;
static const double EPS = 1e-8;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> PI;
#define rep(i,n) for(int i=0;i<(int)(n);++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
#define mp(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define SZ(a) (int(a.size()))
#define F first
#define S second
const double pi=acos(-1);
int dx[]={0,1,0,-1},dy[]={1,0,-1,0};

int X,Y,tx,ty,kx,ky;
int wall[50][50];
bool vis[50][50][50][50];

typedef struct _node{
  int cost,tx,ty,kx,ky;
  int geth()const{
    return (abs(tx-kx)+abs(ty-ky))/2;
  }
  bool operator<(const _node& r)const{
    return cost+geth()>r.cost+r.geth();
  }
  _node (int c,int atx,int aty,int akx,int aky){
    cost=c;
    tx=atx;
    ty=aty;
    kx=akx;
    ky=aky;
  }
}node;

void solve(){
  scanf("%d%d%d%d",&tx,&ty,&kx,&ky);
  --tx,--ty,--kx,--ky;
  rep(i,Y)rep(j,X)scanf("%d",wall[i]+j);
  
  priority_queue<node>q;
  q.push(node(0,tx,ty,kx,ky));
  memset(vis,0,sizeof(vis));
  while(!q.empty()){
    int cc=q.top().cost;
    tx=q.top().tx;
    ty=q.top().ty;
    kx=q.top().kx;
    ky=q.top().ky;
    int h=q.top().geth();
    q.pop();
    if(cc+h>=100 || vis[tx][ty][kx][ky])continue;
    vis[tx][ty][kx][ky]=true;
    if(tx==kx && ty==ky){
      printf("%d\n",cc);
      return;
    }
    rep(i,4){
      int ntx=tx+dx[i],nty=ty+dy[i];
      int nkx=kx-dx[i],nky=ky-dy[i];

      if(0>ntx || ntx>=X ||
         0>nty || nty>=Y ||
         wall[nty][ntx])ntx=tx,nty=ty;
      if(0>nkx || nkx>=X ||
         0>nky || nky>=Y ||
         wall[nky][nkx])nkx=kx,nky=ky;
      if(vis[ntx][nty][nkx][nky])continue;
      q.push(node(cc+1,ntx,nty,nkx,nky));
    }
  }
  printf("NA\n");
}

main(){
  while(scanf("%d%d",&X,&Y),X)
    solve();
}

C++: #include<bits/stdc++.h>
using namespace std;
#define fi first
#define sc second
#define pb push_back
typedef pair<int,int> P;
typedef pair<P,P> PP;
typedef pair<int,PP> PPP;
int dx[4]={-1,0,0,1};
int dy[4]={0,-1,1,0};
int S[51][51][51][51];
int S1[51][51][51][51];
int main()
{
	while(true){
		int X,Y;
		int tx;int ty;
		int kx;int ky;
		scanf("%d%d",&X,&Y);
		if(X==0&&Y==0)break;
		scanf("%d%d%d%d",&tx,&ty,&kx,&ky);tx--;ty--;kx--;ky--;
		int grid[51][51];
		for(int i=0;i<Y;i++){
			for(int j=0;j<X;j++){
				scanf("%d",&grid[i][j]);
			}
		}
		
		for(int i=0;i<Y;i++){
			for(int j=0;j<X;j++){
				for(int k=0;k<Y;k++){
					for(int l=0;l<X;l++){
						S[i][j][k][l]=1001;
						S1[i][j][k][l]=1001;
					}
				}
			}
		}
		
		priority_queue<PPP>s;
		PP x;
		x.fi.sc=tx;x.fi.fi=ty;x.sc.sc=kx;x.sc.fi=ky;
		s.push(PPP(0,x));
		int ans=1001;
		while(!s.empty()){
			//printf("%d\n",(int)s.size());
			PPP p=s.top();s.pop();
			if(S[p.sc.fi.fi][p.sc.fi.sc][p.sc.sc.fi][p.sc.sc.sc]<=p.fi)continue;
			
			if(p.sc.fi.fi==p.sc.sc.fi&&p.sc.fi.sc==p.sc.sc.sc){
				ans=min(ans,p.fi);
				
			}
			if(ans<=p.fi+1)continue;
			S[p.sc.fi.fi][p.sc.fi.sc][p.sc.sc.fi][p.sc.sc.sc]=p.fi;
			S1[p.sc.fi.fi][p.sc.fi.sc][p.sc.sc.fi][p.sc.sc.sc]=p.fi;
			if(p.fi==100)continue;
			for(int k=0;k<4;k++){
				PP t;
				if(p.sc.fi.fi+dy[k]<0||p.sc.fi.fi+dy[k]>=Y||p.sc.fi.sc+dx[k]<0||p.sc.fi.sc+dx[k]>=X){
					t.fi.fi=p.sc.fi.fi;t.fi.sc=p.sc.fi.sc;
				}
				else if(grid[p.sc.fi.fi+dy[k]][p.sc.fi.sc+dx[k]]==1){
					t.fi.fi=p.sc.fi.fi;t.fi.sc=p.sc.fi.sc;
				}
				else{
					t.fi.sc=p.sc.fi.sc+dx[k];t.fi.fi=p.sc.fi.fi+dy[k];
				}
				if(p.sc.sc.fi-dy[k]<0||p.sc.sc.fi-dy[k]>=Y||p.sc.sc.sc-dx[k]<0||p.sc.sc.sc-dx[k]>=X){
					t.sc.sc=p.sc.sc.sc;t.sc.fi=p.sc.sc.fi;
				}
				else if(grid[p.sc.sc.fi-dy[k]][p.sc.sc.sc-dx[k]]==1){
					t.sc.sc=p.sc.sc.sc;t.sc.fi=p.sc.sc.fi;
				}
				else{
					t.sc.fi=p.sc.sc.fi-dy[k];t.sc.sc=p.sc.sc.sc-dx[k];
				}
				if(S[t.fi.fi][t.fi.sc][t.sc.fi][t.sc.sc]<=p.fi+1)continue;
				if(S1[t.fi.fi][t.fi.sc][t.sc.fi][t.sc.sc]<=p.fi+1)continue;
				S1[t.fi.fi][t.fi.sc][t.sc.fi][t.sc.sc]=p.fi+1;
				s.push(PPP(p.fi+1,t));
			}
		}
		if(ans==1001)printf("NA\n");
		else printf("%d\n",ans);
		
	}
	return 0;
}