permutations


Given a collection of distinct numbers, return all possible permutations.

For example,
[1,2,3] have the following permutations:

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[
[1,2,3],
[1,3,2],
[2,1,3],
[2,3,1],
[3,1,2],
[3,2,1]
]

Solution

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public class {
public List<List<Integer>> permute(int[] nums) {
LinkedList<List<Integer>> result = new LinkedList<List<Integer>>();
result.add(new ArrayList<Integer>());
for(int n : nums) {
int size = result.size();
for(;size>0;size--) {
List<Integer> each = result.pollFirst();
for(int i=0; i<=each.size();i++) {
List<Integer> e = new ArrayList<Integer>(each);
e.add(i,n);
result.add(e);
}
}
}
return result;
}
}