Go: package main

import (
    "bufio"
    "os"
    "fmt"
)

var sc = bufio.NewScanner(os.Stdin)

/**************  Cell  *****************/
type Cell struct {
    item interface{}
    next *Cell
    prev *Cell
}

func NewCell(x interface{}, ne *Cell, pr *Cell) *Cell {
    newCp := new(Cell)
    newCp.item = x
    newCp.next = ne
    newCp.prev = pr
    return newCp
}
/************  End Cell  ***************/

/**************  Queue  ****************/
type Queue struct {
    size int
    front *Cell
    rear *Cell
}

func NewQueue() *Queue {
    return new(Queue)
}

func (q *Queue) Push(x interface{}) {
    newNode := NewCell(x, nil, nil)
    if q.size == 0 {
        q.front = newNode
        q.rear = newNode
    } else {
        newNode.prev = q.rear
        q.rear.next = newNode
        q.rear = newNode
    }
    q.size++
}

func (q *Queue) PopLeft() interface{} {
    if q.size == 0 {
        return nil
    } else {
        x := q.front.item
        if q.size == 1 {
            q.front = nil
            q.rear = nil
        } else {
            q.front = q.front.next
            q.front.prev = nil
        }
        q.size--
        return x
    }
}

func (q *Queue) IsEmpty() bool {
    return q.size == 0
}

func (q *Queue) Length() int {
    return q.size
}

type State struct {
    color string
    cnt int
}

func main() {
    for {
        sc.Scan()
        init := sc.Text()
        if init == "0" {
            break
        }
        bfs(init)
    }
}

func bfs(init string) {
    dic := make(map[string]int)
    que := NewQueue()
    que.Push(State{init, 0})
    length := len(init)
    isSolved := false
    for !que.IsEmpty() {
        state := que.PopLeft().(State)
        _, ok := dic[state.color]
        if ok {
            continue
        } else {
            dic[state.color] = state.cnt
        }

        if isSingleColor(state.color) {
            fmt.Println(state.cnt)
            isSolved = true
            break
        }

        for i := 0;i < length - 1; i++ {
            color1, color2 := string(state.color[i]), string(state.color[i + 1])
            if color1 != color2 {
                color3 := other(color1, color2)
                if i <= length - 2 {
                    que.Push(State{state.color[:i] + color3 + state.color[i + 2:], state.cnt + 1})
                } else {
                    que.Push(State{state.color[:i] + color3, state.cnt + 1})
                }
            }
        }
    }
    if !isSolved {
        fmt.Println("NA")
    }
}

func other(color1, color2 string) string {
    if color1 == "r" {
        if color2 == "g" {
            return "bb"
        } else if color2 == "b" {
            return "gg"
        }
    } else if color1 == "g" {
        if color2 == "r" {
            return "bb"
        } else if color2 == "b" {
            return "rr"
        }
    } else if color1 == "b" {
        if color2 == "r" {
            return "gg"
        } else if color2 == "g" {
            return "rr"
        }
    }
    return ""
}

func isSingleColor(color string) bool {
    for _, c := range color {
        if string(c) != string(color[0]) {
            return false
        }
    }
    return true
}

C++: #include <list>
#include <stdio.h>
#include <algorithm>

using namespace std;


typedef struct {
	char nood[11];
	int time;
} WORM;

unsigned int makeHash(char nood[])
{
	int i = 0;
	unsigned int ret = 0;
	while (nood[i] != -1){
		ret += nood[i];
		ret *= 3;
		i++;
	}
	
	return (ret);
}

int add_worm(list<WORM>* lstWorm, list<unsigned>& lstHash)
{
	WORM add;
	
	add.time = lstWorm->front().time + 1;
	
	int i = 0;
	while (lstWorm->front().nood[i + 1] != -1){
		if (lstWorm->front().nood[i] != lstWorm->front().nood[i + 1]){
			memcpy(add.nood, lstWorm->front().nood, 11);
			add.nood[i] = add.nood[i + 1] = 3 - (lstWorm->front().nood[i] + lstWorm->front().nood[i + 1]);
			if (find(lstHash.begin(), lstHash.end(), makeHash(add.nood)) == lstHash.end()){
				lstWorm->push_back(add);
				lstHash.push_back(makeHash(add.nood));
			}
		}
		i++;
	}
	
	return (0);
}

bool checkNood(char nood[])
{
	int i = 1;
	int d = nood[0];
	bool ret = true;
	
	while (nood[i] != -1){
		if (d != nood[i]){
			ret = false;
			break;
		}
		i++;
	}
	
	return (ret);
}

int main(void)
{
	list<unsigned int> lstHash;
	list<WORM> lstWorm;
	WORM add;
	
	while (1){
		lstHash.clear();
		lstWorm.clear();
		scanf("%s", add.nood);
		if (add.nood[0] == '0'){
			break;
		}
		int i = 0;
		while (add.nood[i] != '\0'){
			switch(add.nood[i]){
			  case 'r': add.nood[i] = 0; break;
			  case 'g': add.nood[i] = 1; break;
			  case 'b': add.nood[i] = 2; break;
			}
			i++;
		}
		add.nood[i] = -1;
		add.time = 0;
		
		lstWorm.push_back(add);
		lstHash.push_back(makeHash(add.nood));
		
		while (lstWorm.empty() == false && checkNood(lstWorm.front().nood) == false){
			add_worm(&lstWorm, lstHash);
			lstWorm.pop_front();
		}
		
		if (lstWorm.empty() == true){
			puts("NA");
		}
		else {
			printf("%d\n", lstWorm.front().time);
		}
	}
	
	return (0);
}

C++: #include<iostream>
#include<string>
#include<queue>
#include<map>
using namespace std;
int main(){

  string s,str,col[3];
  queue<string> que;
  map<string,int> mp;
  int flag;
  while(1){
    cin >> s;
    if(s == "0") break;
    flag = 1;
    que.push(s);
    mp[s] = 0;
    for(int i=0;i<3;i++) col[i] = "";
    for(int i=0;i<s.size();i++){
      col[0] += "r";
      col[1] += "b";
      col[2] += "g";
    }
    while(!que.empty()){
      if(que.front()==col[0]){
	cout << mp[col[0]] << endl;
	flag--;
	break;
      }
      if(que.front()==col[1]){
	cout << mp[col[1]] << endl;
	flag--;
	break;
      }
      if(que.front()==col[2]){
	cout << mp[col[2]] << endl;
	flag--;
	break;
      }
      
      for(int i=0;i<s.size()-1;i++){
	str = que.front();
	if(str[i] != str[i+1]){
	  if(str[i] != 'r' && str[i+1] != 'r'){
	    str[i] = 'r';
	    str[i+1] = 'r';
	  } else if(str[i] != 'b' && str[i+1] != 'b'){
	    str[i] = 'b';
	    str[i+1] = 'b';
	  }else if(str[i] != 'g' && str[i+1] != 'g'){
	    str[i] = 'g';
	    str[i+1] = 'g';
	  }
	  if(mp.count(str) == 0){
	    que.push(str);
	    mp[str] = mp[que.front()]+1;
	  }
	}
      }
      que.pop();
    }
    while(!que.empty()) que.pop();
    if(flag) cout << "NA" << endl;
  }
  return (0);
}

C++: #include "bits/stdc++.h"
using namespace std;

int main(){
  while(true){
    string s;
    cin>>s;
    if(s=="0")break;
    string sr(s.size(),'r');
    string sg(s.size(),'g');
    string sb(s.size(),'b');
    map<string,int> mp;
    queue<string> q;
    q.push(s);
    mp[s]=0;
    int f=0;
    if(s==sr||s==sb||s==sg){
      cout<<0<<endl;
    }else{
      //for(int i=0;i<1e6;i++){
      while(!q.empty()){
        string x=q.front();
        q.pop();
        for(int j=0;j<s.size()-1;j++){
          string y=x;
          if(y[j]=='r'&&y[j+1]=='g'){
            y[j]='b';
            y[j+1]='b';
          }else if(y[j]=='b'&&y[j+1]=='g'){
            y[j]='r';
            y[j+1]='r';
          }else if(y[j]=='r'&&y[j+1]=='b'){
            y[j]='g';
            y[j+1]='g';
          }else if(y[j]=='g'&&y[j+1]=='b'){
            y[j]='r';
            y[j+1]='r';
          }else if(y[j]=='g'&&y[j+1]=='r'){
            y[j]='b';
            y[j+1]='b';
          }else if(y[j]=='b'&&y[j+1]=='r'){
            y[j]='g';
            y[j+1]='g';
          }
          //cout<<mp[x]+1<<" "<<y<<endl;
          if(y==sr||y==sb||y==sg){
            cout<<mp[x]+1<<endl;
            f=1;
            break;
          }
          if(mp[y]==0){
            mp[y]=mp[x]+1;
            q.push(y);
          }
        }
        if(f)break;
      }
      if(!f)cout<<"NA"<<endl;
    }
  }
}