Go: /*
http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=2006&lang=jp
Keitai Message
*/

package main

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

// 標準入力を取得するScannerのインスタンスを作成
var scanner = bufio.NewScanner(os.Stdin)

// 標準入力で各行を読み込みstringとして返す
func readLine() string {
	if scanner.Scan() {
		return scanner.Text()
	}
	return ""
}

func main() {
	// 1: . , ! ? (スペース)
	// 2: a b c
	// 3: d e f
	// 4: g h i
	// 5: j k l
	// 6: m n o
	// 7: p q r s
	// 8: t u v
	// 9: w x y z
	// 0: 確定ボタン

	// 改行から空白区切りに変更
	scanner.Split(bufio.ScanWords)
	line, _ := strconv.Atoi(readLine()) // 5行標準入力が続く

	table := []string{
		"",      // 0 index調整ためダミーデータ
		".,!? ", // 1
		"abc",   // 2
		"def",   // 3
		"ghi",   // 4
		"jkl",   // 5
		"mno",   // 6
		"pqrs",  // 7
		"tuv",   // 8
		"wxyz"}  // 9

	// 5行分の標準入力を格納するsliceを作成する
	messages := make([]string, 0, line)

	// sliceに標準入力の内容を格納する
	for i := 0; i < line; i++ {
		messages = append(messages, readLine()) // messages=[20 220 222220 44033055505550666011011111090666077705550301110 000555555550000330000444000080000200004440000]
	}

	// 各行毎に解析する
	for _, message := range messages { // message=000555555550000330000444000080000200004440000
		// 0で分割する
		messageSlice := strings.Split(message, "0") // messageSlice=[   55555555    33    444    8    2    444    ]
		for _, word := range messageSlice {
			if word == "" {
				// NOP.
				// 0をセパレーターにしているので空文字がsliceに格納されてい箇所がある
				// 何もしない
			} else { // word=55555555
				// 一文字取り出しコード値をASCII文字に変換する
				ascii := string((word[0])) // word[0]=5

				// ASCII文字からintへ変換する(tableのindexになる)
				number, _ := strconv.Atoi(ascii)

				// 入力回数をカウントする
				count := len(word) // 5

				// 同じ数字を続けて入力すると変化する文字はループすることを考慮する
				for count > len(table[number]) { // 5 > 3
					count -= len(table[number]) // 2
				}

				// キー配列
				keys := table[number]                   //jkl
				fmt.Printf("%s", string(keys[count-1])) //k
			}
		}
		fmt.Println() // 改行
	}
}

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

#define rep(i,j) for(int (i)=0;(i)<(j);++(i))

int main() {
    string code[9];
    code[0] = ".,!? ";
    code[1] = "abc";
    code[2] = "def";
    code[3] = "ghi";
    code[4] = "jkl";
    code[5] = "mno";
    code[6] = "pqrs";
    code[7] = "tuv";
    code[8] = "wxyz";
    int n;
    cin >> n;
    rep(i, n) {
        string c;
        cin >> c;
        int idx = -1, cnt = -1;
        rep(j, c.length()) {
            string t = "";
            t += c[j];
            int num = atoi(t.c_str());
            if (num == 0) {
                if (idx != -1 && cnt != -1) cout << code[idx][cnt];
                idx = -1;
                cnt = -1;
            }
            else {
                if (idx == -1 && cnt == -1) {
                    idx = num-1;
                    cnt = 0;
                }
                else {
                    cnt = (cnt+1)%code[idx].length();
                }
            }
        }
        cout << endl;
    }
}

C++: #include<bits/stdc++.h>
using namespace std;
int main(){
  string table[]={"",".,!? ","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};
  char str[1280];
  int a;
  cin>>a;
  for(int i=0;i<a;i++){
    cin>>str;
    int r=0;
    char now='0';
    for(int i=0;str[i];i++){
            if(now!=str[i]){
                if(now!='0'){
		  cout<<table[now-'0'][(r-1)%table[now-'0'].size()];
                }
                r=1;
                now=str[i];
            }else r++;
    }
	    cout<<endl;
  }
  return 0;
}

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

#define FOR(i,k,n) for (int i=(k); i<(int)(n); ++i)
#define REP(i,n) FOR(i,0,n)

using namespace std;

const int INF = 1000000000;
const double eps = 1e-8;

int main(void) {
  string tb[] = {"",".,!? ","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};
  int sz[]={0,5,3,3,3,3,3,4,3,4};
  int n;cin>>n;
  REP(i,n){
    string s;
    cin>>s;
    int cnt = 0;
    int ochar = 0;
    REP(j,s.size()){
      if(s[j]=='0'){
        if(ochar!=0)
          cout<<tb[ochar][cnt%sz[ochar]];
        ochar = 0;
        cnt=0;
      }else{
        if(ochar==(s[j]-'0'))
          cnt++;
        else{
          cnt=0;
          ochar=s[j]-'0';
        }
      }
    }
    cout<<endl;
  }
  return 0;
}

C++: #include <iostream>
#include <string>
#include <vector>
using namespace std;
typedef long long int lli;

string charset[10][5] = {
	{},
	{".", ",", "!", "?", " "},
	{"a", "b", "c"},
	{"d", "e", "f"},
	{"g", "h", "i"},
	{"j", "k", "l"},
	{"m", "n", "o"},
	{"p", "q", "r", "s"},
	{"t", "u", "v"},
	{"w", "x", "y", "z"}
};
int loop[10] = {0, 5, 3, 3, 3, 3, 3, 4, 3, 4};

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);

	int N;
	cin >> N;
	for (int n = 0; n < N; n++){
		string s;
		cin >> s;

		int i = 0;
		int push = -1;
		string ans = "";
		while (i < s.length()){
			int num = stoi(s.substr(i, 1));
			if (num != 0){
				int thisnum = num;
				while (num != 0){
					push++;
					i++;
					num = stoi(s.substr(i, 1));
				}
				ans += charset[thisnum][push % loop[thisnum]];
				push = -1;
			}
			i++;
		}
		cout << ans << endl;
	}

	return 0;
}

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

int main(void){
  int n, i, cnt;
  string str, ans;
  char init;
  vector<string> mp{"", ".,!? ","abc","def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};
  cin >> n;
  while(n--){
    cin >> str;
    cout << str << endl;
    ans = "";
    i = 0;
    while(i < str.length()){
      while(str[i] == '0'){
        i++;
      }
      if(i >= str.length()){
        break;
      }
      init = str[i];
      cnt = 0;
      while(i < str.length() and str[i] == init){
        i++;
        cnt++;
      }
      ans += mp[init - '0'][(cnt - 1) % mp[init - '0'].length()];
    }
    cout << ans << endl;
  }
  return 0;
}

C++: #include <iostream>
#include <string>
#include <vector>
using namespace std;
int main(){
  string key[10]={"0",".,!? ","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};
  int n;
  cin>>n;
  for (int nn=0;nn<n;nn++){
    string in;
    vector<int> input;
    string ans;
    cin>>in;
    for (int i=0;i<in.length();i++){
      input.push_back(in[i]-48);
    }
    int count=0;
    int cc=0;
    for (int i=0;i<in.length();i++){
      if (input[i]==0&&i!=0&&count!=0){
	char c=key[input[i-1]][(count-1)%key[input[i-1]].size()];
	ans[cc]=c;
	cc++;
	count=0;
	continue;
      }
      else if (input[i]==0&&i==0)
	continue;
      else if (input[i]==0&&count==0)
	continue;
      else
	count++;
    }
    for (int i=0;i<cc;i++){
      cout<<ans[i];
    }
    cout<<endl;
  }
}

C++: #include <iostream>
#include <vector>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <algorithm>

using namespace std;
using vi = vector<int>;
using vvi = vector<vi>;
template<class T> using hset = unordered_set<T>;
template<class Key, class T> using hmap = unordered_map<Key, T>;

int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};
vector<vector<char> > phone = {
    {},
    {' ', '.', ',', '!', '?'},
    {'c', 'a', 'b'},
    {'f', 'd', 'e'},
    {'i', 'g', 'h'},
    {'l', 'j', 'k'},
    {'o', 'm', 'n'},
    {'s', 'p', 'q', 'r'},
    {'v', 't', 'u'},
    {'z', 'w', 'x', 'y'}
};

int main() {
    int n; cin >> n;
    string s;
    for (int i = 0; i < n; i++) {
        cin >> s;
        int k = 0, kl = 0;
        for (char c : s) {
            if (c - '0' == 0) {
                if (kl == 0) continue;
                cout << phone[kl][k];
                k = 0;
                kl = 0;
            } else {
                kl = c - '0';
                k = (k+1) % phone[kl].size();
            }
        }
        cout << endl;
    }
    return 0;
}