static List<Answer> solve(int[] numbers) {
int n = numbers.length;
Element[] a = new Element[n];
for (int i = 0; i < n; i++) {
a[i] = new Element(numbers[i], i);
}
int id = -1;
for (int i = 0; i < n; i++) {
if (luckies.contains(a[i].x)) {
id = i;
break;
}
}
Element[] b = a.clone();
Arrays.sort(b);
if (Arrays.equals(a, b)) {
return new ArrayList<Answer>();
}
if (id == -1) {
return null;
}
boolean[] did = new boolean[n];
for (int i = 0; i < n; i++) {
if (a[i] == b[i]) {
did[i] = true;
}
}
List<Answer> ans = new ArrayList<Answer>();
int cur = 0;
while (cur < n) {
while (b[id] != a[id]) {
int newId = b[id].n;
swap(id, b[id].n, ans, a);
did[id] = true;
id = newId;
}
while (cur < n && did[cur] || cur == id) {
cur++;
}
if (cur < n) {
int newId = cur;
swap(cur, id, ans, a);
id = newId;
}
}
// for (int i = 1; i < n; i++) {
// if (a[i].x < a[i - 1].x) {
// throw new AssertionError();
// }
// }
// if (ans.size() > 2 * n) {
// throw new AssertionError();
// }
return ans;
}
