Go: package main

import (
	"bufio"
	"os"
	"strconv"
	"strings"
	"fmt"
)

var scanner = bufio.NewScanner(os.Stdin)

type Point struct {
	x, y int
}

func main() {
	dx := []int{1, 0, -1, 0}
	dy := []int{0, -1, 0, 1}
	maze := make([][]rune, 30)
	for i := range maze {
		maze[i] = make([]rune, 30)
	}
	next := make([][]rune, 30)
	for i := range next {
		next[i] = make([]rune, 30)
	}
	check := make([][]int, 30)
	for i := range check {
		check[i] = make([]int, 30)
	}
	for scanner.Scan() {
		buf := strings.Split(scanner.Text(), " ")
		W, _ := strconv.Atoi(buf[0])
		H, _ := strconv.Atoi(buf[1])
		if W == 0 && H == 0 {
			break
		}
		for i := 0; i < H; i++ {
			scanner.Scan()
			buf_ := scanner.Text()
			for j, v := range buf_ {
				maze[i][j] = v
			}
		}
		man := 0
		for i := 0; i < H; i++ {
			for j := 0; j < H; j++ {
				if maze[i][j] != '.' && maze[i][j] != 'X' && maze[i][j] != '#' {
					switch maze[i][j] {
					case 'E':
						maze[i][j] = 0
						man++
					case 'N':
						maze[i][j] = 1
						man++
					case 'W':
						maze[i][j] = 2
						man++
					case 'S':
						maze[i][j] = 3
						man++
					}
				}
			}
		}
		ans := -1
		for t := 0; t <= 180; t++ {
			if man == 0 {
				ans = t
				break
			}
			for i := 0; i < H; i++ {
				for j := 0; j < W; j++ {
					check[i][j] = 0x7FFFFFFF
				}
			}
			for i := 0; i < H; i++ {
				for j := 0; j < W; j++ {
					if maze[i][j] > 3 {
						continue
					}
					l := (maze[i][j] + 3) % 4
					for k := 0; k < 4; k++ {
						y := i + dy[l]
						x := j + dx[l]
						if 0 <= y && y < H && 0 <= x && x < W && (maze[y][x] == '.' || maze[y][x] == 'X') {
							maze[i][j] = l
							check[y][x] = min(check[y][x], int((l+2)%4))
							break
						}
						l = (l + 1) % 4
					}
				}
			}
			for i := 0; i < H; i++ {
				for j := 0; j < W; j++ {
					next[i][j] = maze[i][j]
				}
			}
			for i := 0; i < H; i++ {
				for j := 0; j < W; j++ {
					if maze[i][j] > 3 {
						continue
					}
					y := i + dy[maze[i][j]]
					x := j + dx[maze[i][j]]
					if 0 <= y && y < H && 0 <= x && x < W && check[y][x] == int((maze[i][j]+2)%4) {
						if maze[y][x] == '.' {
							next[y][x] = maze[i][j]
						} else if maze[y][x] == 'X' {
							man--
						}
						next[i][j] = '.'
					}
				}
			}
			for i := 0; i < H; i++ {
				for j := 0; j < W; j++ {
					maze[i][j]=next[i][j]
				}
			}
		}
		if ^ans != 0 {
			fmt.Println(ans)
		} else {
			fmt.Println("NA")
		}
	}
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

C++: #include <iostream>
#include <string>
using namespace std;

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

int main()
{
	int W,H;
	while(cin >> W >> H, (W||H))
	{
		int cnt=0, p[35][35],tp[35][35],v[35][35];
		char f[35][35];
		
		string t;
		getline(cin, t);
		for(int i=0; i<H; i++)
		{
			getline(cin, t);
			for(int j=0; j<W; j++)
			{
				f[j][i]=t[j];
				p[j][i]=-1;
				if(f[j][i]=='E') p[j][i]=0;
				if(f[j][i]=='N') p[j][i]=1;
				if(f[j][i]=='W') p[j][i]=2;
				if(f[j][i]=='S') p[j][i]=3;
				
				if(p[j][i]!=-1) cnt++;
			}
		}
		
		int ret=0;
		for(; ret<=180; ret++)
		{
			if(cnt==0) break;
			
			for(int i=0; i<H; i++)
			for(int j=0; j<W; j++)
			{
				tp[j][i]=-1;
				v[j][i]=-1;
				
				if(p[j][i]!=-1)
				{
					int next=p[j][i];
					for(int k=0; k<4; k++)
					{
						int d=(p[j][i]+k+3)%4;
						int tx=j+dx[d], ty=i+dy[d];
						if(tx<0||ty<0||tx>=W||ty>=H) continue;
						if(f[tx][ty]=='#'||p[tx][ty]!=-1) continue;
						
						next=d;
						break;
					}
					
					p[j][i]=next;
				}
			}
			
			for(int i=0; i<H; i++)
			for(int j=0; j<W; j++)
			{
				if(p[j][i]!=-1)
				{
					int tx=j+dx[p[j][i]], ty=i+dy[p[j][i]];
					if(v[tx][ty]==-1) v[tx][ty]=p[j][i];
					else if((v[tx][ty]+2)%4>(p[j][i]+2)%4) v[tx][ty]=p[j][i];
				}
			}
			
			for(int i=0; i<H; i++)
			for(int j=0; j<W; j++)
			{
				if(p[j][i]!=-1)
				{
					int tx=j+dx[p[j][i]], ty=i+dy[p[j][i]];
					if(v[tx][ty]==p[j][i]) tp[tx][ty]=p[j][i];
					else tp[j][i]=p[j][i];
				}
			}
			
			for(int i=0; i<H; i++)
			for(int j=0; j<W; j++)
			{
				p[j][i]=tp[j][i];
				if(f[j][i]=='X'&&p[j][i]!=-1)
				{
					cnt--;
					p[j][i]=-1;
				}
			}
		}
		
		if(ret>180) cout << "NA" << endl;
		else cout << ret << endl;
	}
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <string>
#include <vector>
#include <deque>
#include <list>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cmath>
#include <cstring>
#include <cctype>
#include <sstream>
#include <set>
#include <map>
#include <queue>
#include <complex>
using namespace std;
#define REP(i,n) for(int i = 0; i < (int)n; i++)
#define FOR(i,a,b) for(int i = a; i < (int)b; i++)
const int INF = 1<<28;

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

struct P {
	int h, w, d;
	P(int a, int b, int c) {h = a; w = b; d = c;}
	bool operator > (const P& a) const {
		return d > a.d; 
	}
};

int main() {
	int W, H;
	while(cin >> W >> H, W|H) {
		int field[H][W];
		REP(i, H) REP(j, W) {
			char in; cin >> in;
			if(in == '#') field[i][j] = 10;
			else if(in == '.') field[i][j] = 100;
			else if(in == 'X') field[i][j] = 1000;
			else if(in == 'E') field[i][j] = 2;
			else if(in == 'N') field[i][j] = 3;
			else if(in == 'W') field[i][j] = 0;
			else if(in == 'S') field[i][j] = 1;
		}

		queue<P> q;
		priority_queue<P, vector<P>, greater<P> > pq;
		REP(i, H) REP(j, W)
			if(field[i][j] < 4)
				q.push(P(i, j, field[i][j]));

		int cnt = 0;
		while(q.size() | pq.size()) {

			//dicide direction
			while(q.size()) {
				P pp = q.front(); q.pop();
				bool flg = true;
				REP(i, 4) {
					int nd = (pp.d + 3 + i) % 4;
					int nh = pp.h + dy[nd], nw = pp.w + dx[nd];
					if(0 <= nh && 0 <= nw && nh < H && nw < W  && field[nh][nw] > 99) {
						pp.d = nd; pq.push(pp);
						field[pp.h][pp.w] = nd;
						flg = false;
						break;
					}
				}
				if(flg) pq.push(pp);
			}

			//dicide move
			while(pq.size()) {
				P pp = pq.top(); pq.pop();
				int nh = pp.h + dy[pp.d], nw = pp.w + dx[pp.d];
				if(field[nh][nw] > 99) {
					if(field[nh][nw] == 1000)
						field[pp.h][pp.w] = 100;
					else {
						swap(field[pp.h][pp.w], field[nh][nw]);
						q.push(P(nh, nw, pp.d));
					}
				}
				else
					q.push(pp);
			}
			cnt++;
			if(cnt >= 180) break;
		}
		if(cnt >= 180) cout << "NA" << endl;
		else cout << cnt << endl;
	}
	return 0;
}