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 <bits/stdc++.h>
using namespace std;

int w, h;
vector<vector<int>> d;
vector<vector<vector<vector<int>>>> flg;
int movel(int x, int y){
    if(d[x-1][y]==1) return x;
    return x-1;
}
int mover(int x, int y){
    if(d[x+1][y]==1) return x;
    return x+1;
}
int moveu(int x, int y){
    if(d[x][y-1]==1) return y;
    return y-1;
}
int moved(int x, int y){
    if(d[x][y+1]==1) return y;
    return y+1;
}

int bfs(int tx, int ty, int kx, int ky){
    flg.assign(w+2,vector<vector<vector<int>>>(h+2,vector<vector<int>>(w+2,vector<int>(h+2,0))));
    queue<vector<int>> q;
    q.push({tx, ty, kx, ky, 0});
    flg[tx][ty][kx][ty]=1;

    while(!q.empty()){
        int vtx = q.front()[0];
        int vty = q.front()[1];
        int vkx = q.front()[2];
        int vky = q.front()[3];
        int vcnt = q.front()[4];
        q.pop();

        if(vtx==vkx && vty==vky) return vcnt;
        if(vcnt+1<100){
            if(1!=flg[mover(vtx,vty)][vty][movel(vkx, vky)][vky]){
                q.push({mover(vtx,vty),vty,movel(vkx, vky),vky,vcnt+1});
                flg[mover(vtx,vty)][vty][movel(vkx, vky)][vky]=1;
            }
            if(1!=flg[movel(vtx,vty)][vty][mover(vkx, vky)][vky]){
                q.push({movel(vtx,vty),vty,mover(vkx, vky),vky,vcnt+1});
                flg[movel(vtx,vty)][vty][mover(vkx, vky)][vky]=1;
            }
            if(1!=flg[vtx][moveu(vtx,vty)][vkx][moved(vkx, vky)]){
                q.push({vtx,moveu(vtx,vty),vkx,moved(vkx, vky),vcnt+1});
                flg[vtx][moveu(vtx,vty)][vkx][moved(vkx, vky)]=1;
            }
            if(1!=flg[vtx][moved(vtx,vty)][vkx][moveu(vkx, vky)]){
                q.push({vtx,moved(vtx,vty),vkx,moveu(vkx, vky),vcnt+1});
                flg[vtx][moved(vtx,vty)][vkx][moveu(vkx, vky)]=1;
            }
        }
    }
    return -1;
}

int main(){
    while(1){
        cin >> w >> h;
        if(w==0) break;
        int tx, ty, kx, ky;
        cin >> tx >> ty;
        cin >> kx >> ky;
        d.assign(w+2, vector<int>(h+2,1));
        for(int i=1; i<h+1; i++){
            for(int j=1; j<w+1; j++){
                cin >> d[j][i];
            }
        }
        int ans=bfs(tx, ty, kx, ky);
        if(ans==-1){
            cout << "NA" << endl;
        }else{
            cout << ans << endl;
        }
    }
}

C++: #include<iostream>
#include<queue>
#include<cstdio>
#include<cstring>

using namespace std;

#define MAX 51

int xy[MAX][MAX];
int cost[MAX][MAX][MAX][MAX];
int X,Y;

int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};

struct state{
  int tx;
  int ty;
  int kx;
  int ky;
  int co;
  state(){}
  state(int tx,int ty,int kx,int ky,int co):
    tx(tx),ty(ty),kx(kx),ky(ky),co(co){}
};

int solve(int tx,int ty,int kx,int ky){

  memset(cost,101,sizeof(cost));

  queue<state> q;
  q.push( state(tx,ty,kx,ky,0) );

  while( !q.empty() ){
    state p=q.front();
    q.pop();


    cost[tx][ty][kx][ky]=p.co;

    tx=p.tx;
    ty=p.ty;
    kx=p.kx;
    ky=p.ky;

    for(int i=0;i<4;i++){

      if(p.co+1>=100) continue;
      
      if(kx+dx[i]*-1 < 0 || ky+dy[i]*-1 <0 || kx+dx[i]*-1 >= X || ty+dy[i]*-1 >= Y || 
	 tx+dx[i] < 0 || ty+dy[i] <0 || tx+dx[i] >= X || ty+dy[i] >= Y )
	continue;

      if( xy[ty+dy[i]][tx+dx[i]]==1 || xy[ky+dy[i]*-1][kx+dx[i]*-1]==1 )
	continue;
      
      if(tx+dx[i] == kx+dx[i]*-1 && ty+dy[i] == ky+dy[i]*-1)
	return p.co+1;

      if( cost[tx+dx[i]][ty+dy[i]][kx+dx[i]*-1][ky+dy[i]*-1] < p.co)
	continue;

      q.push( state(tx+dx[i],ty+dy[i],kx+dx[i]*-1,ky+dy[i]*-1,p.co+1) );

    }
  }
  return -1;
} 

main(){
  
  int i,j;
  int kx,ky,tx,ty;
  int n;

  while(1){
    
    cin >> X >> Y;

    if(X==0 && Y==0) break;
    
    cin >> tx >> ty;
    cin >> kx >> ky;
    
    for(i=0;i<Y;i++){
      for(j=0;j<X;j++){
	cin >> xy[i][j];
      }
    }
    
    n=solve(tx-1,ty-1,kx-1,ky-1);
    
    if(n==-1)
      cout << "NA" << endl;
    else
      cout << n << endl;
  }
  return 0;
}

C++: #include <cstdio>
#include <cstdlib>
#include <cstring>
#include <utility>
#include <queue>
#include <algorithm>
using namespace std;
typedef pair<int,int> P1;
typedef pair<P1,P1> P2;
typedef pair<int,P2> P3;
int d[50][51];
int dx[]={1,0,-1,0},dy[]={0,1,0,-1};
bool used[50][50][50][50];
int main() {
	int X,Y;
	while(scanf("%d %d",&X,&Y),X) {
		int tx,ty,kx,ky;
		scanf("%d %d",&tx,&ty); tx--;ty--;
		scanf("%d %d",&kx,&ky); kx--;ky--;
		for(int i=0;i<Y;i++) {
			for(int j=0;j<X;j++) scanf("%d",&d[i][j]);
		}
		queue<P3> Q;
		Q.push(P3(0,P2(P1(tx,ty),P1(kx,ky))));
		used[tx][ty][kx][ky]=1;
		bool NA=1;
		while(!Q.empty()) {
			P3 p3=Q.front();Q.pop();
			int tx=p3.second.first.first;
			int ty=p3.second.first.second;
			int kx=p3.second.second.first;
			int ky=p3.second.second.second;
			if(p3.first>100) break;
			if(tx==kx&&ty==ky) {
				printf("%d\n",p3.first);
				NA=0;
				break;
			}
			for(int i=0;i<4;i++) {
				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||d[nty][ntx]) {
					ntx=tx,nty=ty;
				}
				if(0>nkx||nkx>=X||0>nky||nky>=Y||d[nky][nkx]) {
					nkx=kx,nky=ky;
				}
				if(!used[ntx][nty][nkx][nky]) {
					used[ntx][nty][nkx][nky]=1;
					Q.push(P3(p3.first+1,P2(P1(ntx,nty),P1(nkx,nky))));
				}
			}
		}
		if(NA) printf("NA\n");
	}
}