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<iostream>
#include<vector>
#include<queue>
#include<map>
#include<cmath>
#include<cstdlib>
#include<algorithm>
using namespace std;

string ans;

class board{
public:
  int h,c;
  string s;
  board(int x,int y,string z){ h=x; c=y; s=z;}
  const bool operator<(const board x)const{return (h+c>x.h+x.c) || (h+c==x.h+x.c && c>x.c); }
};

int score(string s){
  int res=0;
  for(int i=0;i<25;i++){
    if(s[i]!='x'){
      int m=20;
      for(int j=0;j<25;j++){
	if(s[i]==ans[j]){
	  int a = abs(i-j);
	  int tmp = a/5 + a%5;
	  m = min(m,tmp);
	  if(s[i]!='o')break;
	}
      }
      res += m;
    }
  }
  return res;
}

char trans(int x){
  if(!x)return 'o';
  else return 'a'+x-1;
}

int main(){
  string s;
  ans = "xxoxxxabcxdefghxijkxxxoxx";
  int tmp,cost;

  for(;;){
    cin >> tmp;
    if(tmp<0)break;

    s = "xx";
    s += trans(tmp);
    s += "xxx";
    for(int i=0;i<3;i++){
      cin >> tmp;
      s += trans(tmp);
    }
    s += "x";
    for(int i=0;i<5;i++){
      cin >> tmp;
      s += trans(tmp);
    }
    s += "x";
    for(int i=0;i<3;i++){
      cin >> tmp;
      s+= trans(tmp);
    }
    s += "xxx";
    cin >> tmp;
    s += trans(tmp);
    s += "xx";

    priority_queue<board> q1;
    q1.push(board(score(s),0,s));

    map<string,bool> m1;
    m1[s] = 0;
    while(q1.size()){
      board p = q1.top();q1.pop();
      int dx[] = {-5,1,5,-1};
      //cout << p.h << " " << p.c << " " << p.s << endl;
      cost = p.c;
      if(p.s == ans)break;
      if(cost>20)break;

      for(int i=0;i<25;i++){
	if(p.s[i]=='o'){
	  for(int j=0;j<4;j++){
	    int sx = i + dx[j];
	    string str = p.s;
	    if(sx<0 || 25<=sx)continue;
	    if(str[sx] == 'x' || str[sx] == 'o')continue;
	    swap(str[i],str[sx]);
	    if(!m1[str]){
	      q1.push(board(score(str),cost+1,str));
	      m1[str] = cost+1;
	    }
	  }
	}
      }
    }



    if(cost>20)cout << "NA\n";
    else cout << cost << endl;
  }
}

C++: #include<stdio.h>
#include<map>
#include<queue>
typedef long long L;
L S(L l,int a,int b)
{
	L c=(l>>(a*4))&15;
	l&=~(15LL<<(a*4));
	L d=(l>>(b*4))&15;
	l&=~(15LL<<(b*4));
	return l|(c<<(b*4))|(d<<(a*4));
}
int main()
{
	const int di[13][4]={
		{3},
		{3,6},
		{1,2,4,7},
		{3,8},
		{6},
		{2,5,7,10},
		{3,6,8,11},
		{4,7,9,12},
		{8},
		{6,11},
		{7,10,12,13},
		{8,11},
		{11}};
	typedef std::map<L,int>M;
	M m;
	M::iterator ite;
	std::queue<L>q;
	q.push(0xBA9876543210LL);
	q.push(-1);
	int i,j,k;
	for(int x=0;x<=20;)
	{
		L l=q.front();
		q.pop();
		if(l<0)
		{
			q.push(l);
			++x;
			continue;
		}
		ite=m.find(l);
		if(ite!=m.end())continue;
		m[l]=x;
		int a[2];
		for(i=j=0;i<13;++i)
			if( !(l&(15LL<<(i*4))) )
				a[j++]=i;
		for(k=0;k<2;++k)
			for(i=0;i<4;++i)
			{
				int c=di[a[k]][i];
				if(c)
				{
					L t=S(l,a[k],c-1);
					q.push(t);
				}
				else break;
			}
	}
	for(;;)
	{
		L l=0,x;
		for(i=0;i<13;++i)
		{
			if(scanf("%lld",&x),x<0)return 0;
			l|=(x<<(i*4));
		}
		ite=m.find(l);
		ite==m.end()?puts("NA"):printf("%d\n",ite->second);
	}
}