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| public class Solution {
public List<List<Integer>> permute(int[] nums) {
Arrays.sort(nums);
List<List<Integer>> list = new ArrayList<List<Integer>>();
int rht = nums.length - 1;
int j = rht;
list.add(toList(nums));
while(j >= 0) {
j = rht;
while(j-1 >=0 && nums[j] < nums[j-1])j--;
if(j-1 < 0) return list;
int i = j;
while(i<=rht && nums[i] > nums[j-1]) i++;
if(i>rht)i=rht+1;
swap(nums, i-1, j-1);
reverse(nums, j, rht);
list.add(toList(nums));
}
return null;
}
public void reverse(int[] nums, int i, int j) {
int mid = (i+j)/2;
if(mid==nums.length-1)return;
if((i+j)%2==1) {
for(int a = mid; a>=i;a--) {
swap(nums, a, 2*mid-a+1);
}
}else {
for(int a = mid-1; a>=i;a--) {
swap(nums, a, 2*mid-a);
}
}
}
public List toList(int[] nums) {
ArrayList<Object> arrayList = new ArrayList<>();
for(Integer e: nums) {
arrayList.add(e);
}
return arrayList;
}
public void swap(int[] nums, int i, int j) {
int tmp = nums[i];
nums[i] = nums[j];
nums[j] = tmp;
}
public static void main(String[] args) {
int[] nums = {2,6,1};
System.out.println(new Solution().permute(nums).toString());
}
}
|
