Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

const INF = 0x7FFFFFFF

func main() {
	for scanner.Scan() {
		buf := strings.Split(scanner.Text(), " ")
		n, _ := strconv.Atoi(buf[0])
		m, _ := strconv.Atoi(buf[1])
		if n == 0 && m == 0 {
			break
		}
		chair := make([]string, n+1)
		for i := range chair {
			chair[i] = "#"
		}
		chair[n] = "Sentinel"
		for i := 0; i < m; i++ {
			scanner.Scan()
			switch who := scanner.Text(); who {
			case "A": // 左から眺めて行って空いている席があったら即座に座る
				for j := 0; j < n; j++ {
					if chair[j] == "#" {
						chair[j] = "A"
						break
					}
				}
				// log.Println(chair)
				break // 次の人を読み込む
			case "B":
				flag := true
				// 右端からAの隣でない席を探していく
				for j := n-1; j > -1; j-- {
					if chair[j] == "#" && (j == 0 || chair[j-1] != "A") && chair[j+1] != "A" {
						flag = false
						chair[j] = "B"
						break
					}
				}
				// Aの隣しか空いていないので一番左端の空いている席に座る
				if flag {
					for j := 0; j < n; j++ {
						if chair[j] == "#" {
							chair[j] = "B"
							break
						}
					}
				}
				// log.Println(chair)
				break // 次の人を読み込む
			case "C":
				if i == 0 {
					chair[n/2] = "C" // 先客が誰もいないときは真ん中の椅子に座る
				} else {
					for j := 0; j < n; j++ { // 左から舐めて
						if chair[j] != "#" { // その席が空いていなくて
							if chair[j+1] == "#" { // 右隣が空いているなら座る
								chair[j+1] = "C"
								break
							} else if j != 0 && chair[j-1] == "#" { // 右隣が空いていないので左隣に座る
								chair[j-1] = "C"
								break
							}
						}
					}
				}
				// log.Println(chair)
				break // 次の人を読み込む
			case "D":
				distanceTable := make([]int ,n)
				for j := range distanceTable {
					distanceTable[j] = INF
				}
				for j:= 0; j < n; j++ {
					if chair[j] != "#" {
						for k := 0; k < n; k++ {
							distanceTable[k] = min(distanceTable[k], abs(j-k))
						}
					}
				}
				// log.Println("distanceTAble:", distanceTable)
				at := 0
				distance := 0
				for j := 0; j < n; j++ {
					if distance < distanceTable[j] {
						at = j
						distance = distanceTable[j]
					}
				}
				chair[at] = "D"
				// log.Println(chair)
				break // 次の人を読み込む
			}
		}
		for i := 0; i < n; i++ {
			if i == n-1 {
				fmt.Println(chair[i])
			} else {
				fmt.Printf("%s ", chair[i])
			}
		}
	}
}

func min(a, b int) int {
	if a > b {
		return b
	}
	return a
}

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

C++: #include<bits/stdc++.h>
#define rep(i,n)for(int i=0;i<n;i++)
using namespace std;

char s[200], a[2];
int main() {
	bool b;
	int n, m;
	while (scanf("%d%d", &n, &m), n) {
		memset(s, 0, sizeof(s)); rep(i, n)s[i] = '#';
		rep(i, m) {
			scanf("%s", a);
			switch (a[0]) {
			case 'A':
				rep(i, n) { if (s[i] == '#') { s[i] = 'A'; break; } }
				break;
			case 'B':
				b = false;
				for (int i = n - 1; i >= 0; i--) {
					if (s[i] == '#' && (!i || s[i - 1] != 'A') && (i + 1 >= n || s[i + 1] != 'A')) {
						b = true; s[i] = 'B'; break;
					}
				}
				if (!b)rep(i, n) { if (s[i] == '#') { s[i] = 'B'; break; } }
				break;
			case 'C':
				b = false;
				rep(i, n) {
					if (s[i] != '#') {
						if (i + 1 < n&&s[i + 1] == '#') { s[i + 1] = 'C'; b = true; break; }
						if (i&&s[i - 1] == '#') { s[i - 1] == 'C'; b = true; break; }
					}
				}
				if (!b)s[n & 1 ? (n + 1) / 2 : n / 2 + 1] = 'C';
				break;
			case 'D':
				int k, Max = 0;
				rep(i, n) {
					if (s[i] != '#')continue;
					int cnt = INT_MAX;
					int t = i - 1;
					for (; t >= 0 && s[t] == '#'; t--);
					if (t == -1)t = INT_MAX;
					cnt = t;
					t = i + 1;
					for (; t < n&&s[t] == '#'; t++);
					if (t == n)t = INT_MAX;
					cnt = min(cnt, t);
					if (Max < cnt) {
						k = i; Max = cnt;
					}
				}
				s[k] = 'D';
				break;
			}
		}
		printf("%s\n", s);
	}
}

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

int main()
{
	int n,m,i,j,s[102],temp,flag,max,z,count,left,right;
	char k;
	cin>>n>>m;

	while(n!=0){

	for(i=0;i<102;i++)
		s[i]=100;
	for(i=1;i<n+1;i++)
		s[i]=0;

	for(i=0;i<m;i++){
		max=0;
		cin>>k;
		if(k=='A'){
			for(j=1;j<n+1;j++){
				if(s[j]==0){
					s[j]=1;
				break;
				}
			}
		}else if(k=='B'){
			flag=0;
			for(j=n;j>0;j--){
				if(s[j]==0){
					if(s[j+1]!=1 && s[j-1]!=1){
						s[j]=2;
						flag=1;
						break;
					}
					else temp=j;
				}
			}
			if(flag==0){
				s[j]=temp;
				temp=0;
			}
		}else if(k=='C'){
			flag = 0;
			for(j=2;j<n;j++){
				if(s[j]==0 && s[j-1]!=0){
					s[j]=3;
					flag = 1;
					break;
				}
			}
			if(flag ==0){
				if(n%2==0){
					s[n/2+1]=3;
				}
				else {
					s[(n+1)/2]=3;
				}
			}
		}
		else if(k=='D'){
			temp=0;max=0;flag=0;
			for(j=n;j>0;j--){
				if(s[j]==0){
					left=0;right=0;
					for(z=1;;z++){
						if(s[j+z]!=0)
							break;
						else
							right++;
					}

					for(z=1;;z++){
						if(s[j-z]!=0)
							break;
						else 
							left++;
					}
						if(left<right)
							 temp=left;
						else temp=right;
	
				if(temp>=max){
					max=temp;
					flag=j;
				}
				}
			}
			s[flag]=4;
		}
	}


	for(i=1;i<n+1;i++){
		if(s[i]==0)
			cout<<'#';
		else if(s[i]==1)
			cout<<'A';
		else if(s[i]==2)
			cout<<'B';
		else if(s[i]==3)
			cout<<'C';
		else if(s[i]==4)
			cout<<'D';
	}

	cout<<"\n";

	cin>>n>>m;
	}

		return 0;
	}

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

char chair[128];
int n, m;
const int M = 2;

void A() {
	for(int i = 0; i < n; i++) {
		if(chair[i+M] == 'N') {
			chair[i+M] = 'A';
			break;
		}
	}
}

void B() {
	for(int i = n-1; i >= 0; i--) {
		if(chair[i+M] == 'N' && chair[i-1+M] != 'A' && chair[i+1+M] != 'A') {
			chair[i+M] = 'B';
			return;
		}
	}
	for(int i = 0; i < n; i++) {
		if(chair[i+M] == 'N') {
			chair[i+M] = 'B';
			return;
		}
	}
}

void C() {
	for(int i = 0; i < n; i++) {
		if(chair[i+M] == 'N' && (chair[i+1+M] != 'N' || chair[i-1+M] != 'N')) {
			chair[i+M] = 'C';
			return;
		}
	}
	chair[n/2+M] = 'C';
}

void D() {
	int mx = 0;
	int indx = 0;
	for(int i = 0; i < n; i++) {
		if(chair[i+M] == 'N') {
			int mn = 1000;
			for(int j = 0; j < n; j++) {
				if(chair[j+M] != 'N') {
					if(mn > abs(j - i))
						mn = abs(j - i);
				}
			}
			if(mn > mx) {
				mx = mn;
				indx = i;
			}
		}
	}
	chair[indx+M] = 'D';
}

int main() {
	while(cin >> n >> m, n || m) {
		for(int i = 0; i < 128; i++)
			chair[i] = 'N';
		for(int i = 0; i < m; i++) {
			string s;
			cin >> s;
			if(s[0] == 'A')
				A();
			else if(s[0] == 'B')
				B();
			else if(s[0] == 'C')
				C();
			else
				D();
		}
		for(int i = 0; i < n; i++) {
			cout << (chair[i+M] == 'N' ? '#' : chair[i+M]);
		}
		cout << endl;
	}
}