// Derives QFunctions for the given value function and simulates the
// greedy policy for the given number of trials and steps per trial.
// Returns final value of every trial.
public ArrayList simulate(int trials, int steps, long rand_seed) {
ArrayList values = new ArrayList();
_r = new Random(rand_seed);
for (int trial = 1; trial <= trials; trial++) {
System.out.println("\n -----------\n Trial " + trial + "\n -----------");
// Initialize state
_state = new ArrayList();
_nVars = _mdp._alVars.size();
for (int c = 0; c < (_nVars << 1); c++) {
_state.add("-");
}
Iterator i = _mdp._alVars.iterator();
_vars = new TreeSet();
while (i.hasNext()) {
String s = (String) i.next();
if (!s.endsWith("\'")) {
Integer gid = (Integer) _mdp._tmVar2ID.get(s);
_vars.add(gid);
// Note: assign level (level is gid-1 b/c gids in order)
_state.set(gid.intValue() - 1, _r.nextBoolean() ? TRUE : FALSE);
}
}
// System.out.println(_mdp._context.printNode(_mdp._valueDD) + "\n" + _state);
double reward = _mdp._context.evaluate(_mdp._rewardDD, _state);
System.out.print(" " + PrintState(_state) + " " + MDP._df.format(reward));
// Run steps
for (int step = 1; step <= steps; step++) {
// Get action
Action a;
if (_bUseBasis) {
a = getBasisAction();
} else {
a = getAction();
}
// Execute action
executeAction(a);
// Update reward
reward =
(_mdp._bdDiscount.doubleValue() * reward)
+ _mdp._context.evaluate(_mdp._rewardDD, _state);
System.out.println(", a=" + a._sName);
System.out.print(
" " + PrintState(_state) + " " + MDP._df.format(reward) + ": " + "Step " + step);
}
values.add(new Double(reward));
System.out.println();
}
return values;
}
void solve() {
int k = nextInt();
char[] c = nextToken().toCharArray();
for (int i = 0, j = c.length - 1; i < j; i++, j--) {
if (c[i] != '?' && c[j] != '?' && c[i] != c[j]) {
out.println("IMPOSSIBLE");
return;
}
}
int q = 0;
TreeSet<Character> ts = new TreeSet<Character>();
for (int i = 0; i < k; i++) {
ts.add((char) ('a' + i));
}
for (int i = 0, j = c.length - 1; i <= j; i++, j--) {
if (c[i] == '?' && c[j] == '?') {
q++;
}
if (c[i] != '?') {
ts.remove(c[i]);
}
if (c[j] != '?') {
ts.remove(c[j]);
}
}
for (int i = (c.length - 1) / 2, j = c.length - i - 1; i >= 0; i--, j++) {
if (c[i] == '?' && c[j] == '?') {
if (!ts.isEmpty()) {
c[i] = c[j] = ts.pollLast();
} else {
c[i] = c[j] = 'a';
}
}
}
if (!ts.isEmpty()) {
out.println("IMPOSSIBLE");
return;
}
for (int i = 0, j = c.length - 1; i < j; i++, j--) {
if (c[i] == '?') {
c[i] = c[j];
} else if (c[j] == '?') {
c[j] = c[i];
}
}
out.println(new String(c));
}