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| class Solution {
public String getPermutation(int n, int k) {
int[] factorial = new int[n];
factorial[0] = 1;
for (int i = 1; i < factorial.length; i++) {
factorial[i] = i * factorial[i - 1];
}
List<Integer> numList = new LinkedList<>();
for (int i = 1; i <= n; i++) {
numList.add(i);
}
StringBuilder sb = new StringBuilder();
for (int i = n - 1; i >= 0; i--) {
int index = k / factorial[i];
if (k % factorial[i] == 0) {
index--;
}
sb.append(numList.remove(index));
k -= index * factorial[i];
}
return sb.toString();
}
}
|