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 <string>
#include <vector>
#include <queue>
#include <map>
using namespace std;

string s = "0123456789AB";
vector<vector<int>> adj = {
    {2},
    {2,5},
    {0,1,3,6},
    {2,7},
    {5},
    {1,4,6,9},
    {2,5,7,10},
    {3,6,8,11},
    {7},
    {5,10},
    {6,9,11,12},
    {7,10},
    {10}
};
map<string, int> term, dist;

int solve(string stat, string goal, int limit, map<string,int> &dist, bool useterm) {
    dist[stat] = 0;
    queue<string> q;
    q.push(stat);
    while ( ! q.empty()) {
        string s = q.front();
        q.pop();
        if (useterm && term.find(s) != term.end()) {
            return dist[s] + term[s];
        }
        int diff = 0;
        for (int k=0; k<13; ++k) {
            if (s[k] != '0') {
                diff += s[k] != goal[k];
            }
        }
        if ( ! diff) {
            return dist[s];
        }
        if (limit < dist[s] + diff) {
            continue;
        }
        for (int i=0; i<13; ++i) {
            if (s[i] != '0') continue;
            for (int j : adj[i]) {
                string next = s;
                next[i] = s[j];
                next[j] = s[i];
                if (dist.find(next) == dist.end()) {
                    dist[next] = dist[s] + 1;
                    q.push(next);
                }
            }
        }
    }
    return limit + 1;
}

int main() {
    while (1) {
        string stat = "";
        int k;
        for (int i=0; i<13; ++i) {
            if (cin >> k && !~k) return 0;
            stat += s[k];
        }
        int ans = solve("0123456789AB0", stat, 10, term, false);
        if (ans == 11) {
            ans += solve(stat, "0123456789AB0", 10, dist, true);
        }
        if (ans <= 20) {
            cout << ans << endl;
            continue;
        }
        cout << "NA" << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <sstream>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>

using namespace std;

#define FOR(i,k,n) for(int i=(k); i<(int)n; ++i)
#define REP(i,n) FOR(i,0,n)
#define FORIT(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)

struct S{
  vector<int> p;
  int t;
  S(vector<int> p, int t) : p(p),t(t) {}
};

bool operator<(const S& s, const S& t){
  return s.t > t.t;
}
int x[13] = {2,1,2,3,0,1,2,3,4,1,2,3,2};
int y[13] = {4,3,3,3,2,2,2,2,2,1,1,1,0};
int distance(S s){
  int ret = 0;
  REP(i,13){
    if(s.p[i]){
      ret = max(ret, abs(x[i]-x[s.p[i]]) + abs(y[i]-y[s.p[i]]));
    }
  }
  return ret + s.t;
}
void print_s(S s){
  vector<int> v = s.p;
  printf("time:%d\n",s.t);
  printf("    %2d    \n",v[0]);
  printf("  %2d%2d%2d  \n",v[1],v[2],v[3]);
  printf("%2d%2d%2d%2d%2d\n",v[4],v[5],v[6],v[7],v[8]);
  printf("  %2d%2d%2d  \n",v[9],v[10],v[11]);
  printf("    %2d    \n",v[12]);
}

set<vector<int> > memo;
vector<int> goal(13);
int bfs(S start){
  priority_queue<S> que;
  que.push(start);
  while(!que.empty()){
    S s = que.top(); que.pop();
    //print_s(s);
    if(s.t > 20) return -1;
    if(s.p == goal) return s.t;
    if(memo.find(s.p)!=memo.end()) continue;
    memo.insert(s.p);
    if(distance(s) > 20) continue;
    REP(i,13){
      vector<int> tmp = s.p;
      if(s.p[i]==0){
        switch(i){
          case 0:
          case 2:
            swap(tmp[0],tmp[2]);
            que.push(S(tmp,s.t+1));
            break;
          case 12:
          case 10:
            swap(tmp[12],tmp[10]);
            que.push(S(tmp,s.t+1));
            break;
          case 4:
          case 5:
            swap(tmp[4],tmp[5]);
            que.push(S(tmp,s.t+1));
            break;
          case 8:
          case 7:
            swap(tmp[8],tmp[7]);
            que.push(S(tmp,s.t+1));
            break;
        }
        if(i % 4 == 2 || i % 4 == 3){
          tmp = s.p;
          swap(tmp[i],tmp[i-1]);
          que.push(S(tmp,s.t+1));
        }
        if(i % 4 == 1 || i % 4 == 2){
          tmp = s.p;
          swap(tmp[i],tmp[i+1]);
          que.push(S(tmp,s.t+1));
        }
        if(i % 4 != 0 && i < 8){
          tmp = s.p;
          swap(tmp[i],tmp[i+4]);
          que.push(S(tmp,s.t+1));
        }
        if(i % 4 != 0 && i > 4){
          tmp = s.p;
          swap(tmp[i],tmp[i-4]);
          que.push(S(tmp,s.t+1));
        }
      }
    }
  }
}
int main(){
  int n;
  vector<int> p(13);

  REP(i,11) goal[i+1] = i+1;

  while(cin>>p[0], p[0]!=-1){
    for(int i = 1; i < 13; i++){
      cin>>p[i];
    }
    S start(p,0);
    memo.clear();
    int ans = bfs(start);
    if(ans == -1)cout<<"NA"<<endl;
    else cout<< ans << endl;
  }
  return 0;
}