Go: // BFS

package main

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

var scanner = bufio.NewScanner(os.Stdin)

var p = [15]int{}
var g = [13][4]int {
	// -1は存在しないマス目
	{2,-1,-1,-1},
	{2,5,-1,-1},{0,1,3,6},{2,7,-1,-1},
	{5,-1,-1,-1},{1,4,6,9},{2,5,7,10},{3,6,8,11},{7,-1,-1,-1},
	{5,10,-1,-1},{6,9,11,12},{7,10,-1,-1},
	{10,-1,-1,-1},
}

/*
　  ０ １ ２ ３ ４
 0 |／|／|  |／|／|
 1 |／|　|  |　|／|
 2 |　|　|  |　|　|
 3 |／|　|  |　|／|
 4 |／|／|  |／|／|
*/

var row = [13]int{0,1,1,1,2,2,2,2,2,3,3,3,4}
var col = [13]int{2,1,2,3,0,1,2,3,4,1,2,3,2}

type wolf struct {
	m [13]int
}

type pair struct {
	first wolf
	second int
}

func abs(a int) int {
	if a < 0 {
		return -a
	}
	return a
}

func print_board(board [13]int) {
	fmt.Println("--------------------------")
	fmt.Printf("        [%2d]\n", board[0])
	fmt.Printf("    [%2d][%2d][%2d]\n", board[1], board[2], board[3])
	fmt.Printf("[%2d][%2d][%2d][%2d][%2d]\n", board[4], board[5], board[6], board[7], board[8])
	fmt.Printf("    [%2d][%2d][%2d]\n", board[9], board[10], board[11])
	fmt.Printf("        [%2d]\n", board[12])
	fmt.Println("--------------------------")
}

func main() {
	for scanner.Scan() {
		p1, _ := strconv.Atoi(scanner.Text())
		if p1 == -1 {
			break
		}
		p[0]= p1
		scanner.Scan()
		buf1 := strings.Split(scanner.Text(), " ")
		p2, _ := strconv.Atoi(buf1[0])
		p3, _ := strconv.Atoi(buf1[1])
		p4, _ := strconv.Atoi(buf1[2])
		p[1], p[2], p[3] = p2, p3, p4
		scanner.Scan()
		buf2 := strings.Split(scanner.Text(), " ")
		p5, _ := strconv.Atoi(buf2[0])
		p6, _ := strconv.Atoi(buf2[1])
		p7, _ := strconv.Atoi(buf2[2])
		p8, _ := strconv.Atoi(buf2[3])
		p9, _ := strconv.Atoi(buf2[4])
		p[4], p[5], p[6], p[7], p[8] = p5, p6, p7, p8, p9
		scanner.Scan()
		buf3 := strings.Split(scanner.Text(), " ")
		p10, _ := strconv.Atoi(buf3[0])
		p11, _ := strconv.Atoi(buf3[1])
		p12, _ := strconv.Atoi(buf3[2])
		p[9], p[10], p[11] = p10, p11, p12
		scanner.Scan()
		p13, _ := strconv.Atoi(scanner.Text())
		p[12] = p13
		S := make(map[wolf]struct{})
		st := wolf{}
		for i := 0; i < 13; i++ {
			st.m[i] = p[i]
		}
		Q := make([]pair, 0)
		S[st] = struct{}{}
		Q = append(Q, pair{st, 0})
		yet := true
		for len(Q) > 0 {
			at := Q[0].first
			// print_board(at.m)
			cost := Q[0].second
			Q = Q[1:]
			ok := true
			for i :=1; i < 12; i++ {
				if at.m[i] != i {
					ok = false
				}
			}
			if ok {
				// print_board(at.m)
				yet = false
				fmt.Println(cost)
				break
			}
			now := cost
			for i := 0; i < 13; i++ {
				if at.m[i] != 0 {
					now += abs(row[i]-row[at.m[i]]) + abs(col[i]-col[at.m[i]])
				}
			}
			if now > 20 {
				continue
			}
			for i := 0; i < 13; i++ {
				if at.m[i] == 0 {
					for j := 0; j < 4; j++ {
						if ^g[i][j] != 0 {
							at.m[i], at.m[g[i][j]] = at.m[g[i][j]], at.m[i]
							if _, ok := S[at]; !ok {
								S[at] = struct{}{}
								Q = append(Q, pair{at, cost+1})
							}
							at.m[i], at.m[g[i][j]] = at.m[g[i][j]], at.m[i]
						}
					}
				}
			}
		}
		if yet {
			fmt.Println("NA")
		}
	}
}

C++: #include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <cmath>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <list>
#include <iostream>
#include <sstream>
#include <climits>
#include <cfloat>
#include <complex>

using namespace std;

typedef long long ll;

ll encode(int* state)
{
	ll res = 0;
	for (int i = 0; i < 13; ++i)
		res = res << 4 | state[i];
	return res;
}
void decode(int* d, ll e)
{
	for (int i = 12; i >= 0; --i, e >>= 4)
		d[i] = e & 15;
}

map<ll, int> minSteps;
int dir[] = { -1, 1, -2, 2, -4, 4 };
map<int, bool> ok[3];

const int InitialDepth = 14;
map<ll, int> problemSteps;

int start_from_initial(ll current, ll next)
{
	bool newState = minSteps.count(next) == 0;
	if (newState)
		minSteps[next] = minSteps[current] + 1;

	return newState && minSteps[next] < InitialDepth ? 0 : -1;
}
int start_from_problem(ll current, ll next)
{
	bool newState = problemSteps.count(next) == 0;
	if (newState)
		problemSteps[next] = problemSteps[current] + 1;

	if (minSteps.count(next))
		return problemSteps[next] + minSteps[next];

	return newState && problemSteps[next] < 20 - InitialDepth ? 0 : -1;
}
int bfs(ll initial, int (*f)(ll, ll))
{
	queue<ll> q;
	q.push(initial);

	while (!q.empty())
	{
		ll e = q.front();
		q.pop();
		int d[13];
		decode(d, e);

		int zero_pos[2];
		for (int i = 0, j = 0; j < 2; ++i)
			if (!d[i])
				zero_pos[j++] = i;

		for (int i = 0; i < 2; ++i)
		{
			for (int j = 0; j < 6; ++j)
			{
				int a = zero_pos[i];
				int b = a + dir[j];
				if (a > b)
					swap(a, b);
				if (a < 0 || b > 12 || !d[a] && !d[b] || !ok[j/2][a])
					continue;

				int copy[13];
				memcpy(copy, d, sizeof(copy));
				swap(copy[a], copy[b]);
				ll next = encode(copy);

				int r = f(e, next);
				if (r == 0)
					q.push(next);
				else if (r > 0)
					return r;
			}
		}
	}

	return -1;
}

int main()
{
	int o[][9] = {
		{ 1, 2, 4, 5, 6, 7, 9, 10, -1 },
		{ 0, 10, -1 },
		{ 1, 2, 3, 5, 6, 7, -1 }
	};
	for (int i = 0; i < 3; ++i)
		for (int j = 0; o[i][j] != -1; ++j)
			ok[i][o[i][j]] = true;

	int initial[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 0 };
	ll t = encode(initial);
	minSteps[t] = 0;

	bfs(t, start_from_initial);

	while (true)
	{
		int d[13];
		for (int i = 0; i < 13; ++i)
			scanf("%d", d + i);
		if (d[0] == -1)
			break;

		int ans = -1;
		ll s = encode(d);
		if (minSteps.count(s))
			ans = minSteps[s];
		else
		{
			problemSteps.clear();
			ans = bfs(s, start_from_problem);
		}

		if (ans != -1)
			printf("%d\n", ans);
		else
			puts("NA");
	}

	return 0;
}

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

unsigned long long int makeID( int (&p)[ 13 ] )
{
	unsigned long long int ret = 0;
	for( int i = 0; i < 13; ++i ){
		ret *= 13;
		ret += p[ i ];
	}
	return ret;
}

unsigned long long int slide( unsigned long long int s, int a, int b )
{
	int p[ 13 ];
	for( int i = 0; i < 13; ++i ){
		p[ 12 - i ] = s % 13;
		s /= 13;
	}
	int t = p[ a ];
	p[ a ] = p[ b ];
	p[ b ] = t;
	return makeID( p );
}

int main()
{
	map< unsigned long long int, int > ans;
	queue< unsigned long long int > q;

	int side[][ 4 ] = {
		{ -1, -1,  2, -1 },
		{ -1,  2,  5, -1 },
		{  0,  3,  6,  1 },
		{ -1, -1,  7,  2 },
		{ -1,  5, -1, -1 },
		{  1,  6,  9,  4 },
		{  2,  7, 10,  5 },
		{  3,  8, 11,  6 },
		{ -1, -1, -1,  7 },
		{  5, 10, -1, -1,},
		{  6, 11, 12,  9 },
		{  7, -1, -1, 10 },
		{ 10, -1, -1, -1 }
	};

	int p[ 13 ];
	for( int i = 0; i < 13; ++i ){
		p[ i ] = i;
	}
	p[ 12 ] = 0;
	unsigned long long int s = makeID( p );
	ans[ s ] = 0;
	q.push( s );

	int cnt = 1;
	while( cnt <= 20 ){
		int size = q.size();
		for( int i = 0; i < size; ++i ){
			s = q.front();
			q.pop();
			int pos[ 2 ], a = 0;
			unsigned long long int t = s;
			for( int j = 0; j < 13; ++j ){
				int b = t % 13;
				if( b == 0 ) pos[ a++ ] = 12 - j;
				t /= 13;
			}
			for( int j = 0; j < 2; ++j ){
				int b = pos[ j ];
				for( int k = 0; k < 4; ++k ){
					int c = side[ b ][ k ];
					if( c == -1 ) continue;
					t = slide( s, b, c );
					if( ans.find( t ) == ans.end() ){
						ans[ t ] = cnt;
						q.push( t );
					}
				}
			}
		}
		++cnt;
	}

	while( cin >> p[ 0 ] && p [ 0 ] != -1 ){
		for( int i = 1; i < 13; ++i ){
			cin >> p[ i ];
		}
		s = makeID( p );
		if( ans.find( s ) != ans.end() ){
			cout << ans[ s ] << endl;
		}else{
			cout << "NA" << endl;
		}
	}

	return 0;
}