LeetCode-in-All
46. Permutations
Medium
Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.
Example 1:
Input: nums = [1,2,3]
Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
Example 2:
Input: nums = [0,1]
Output: [[0,1],[1,0]]
Example 3:
Input: nums = [1]
Output: [[1]]
Constraints:
1 <= nums.length <= 6-10 <= nums[i] <= 10- All the integers of
numsare unique.
Solution
# @param {Integer[]} nums
# @return {Integer[][]}
def permute(nums)
return [] if nums.nil? || nums.empty?
final_result = []
permute_recur(nums, final_result, [], Array.new(nums.length, false))
final_result
end
private
def permute_recur(nums, final_result, curr_result, used)
if curr_result.length == nums.length
final_result << curr_result.dup
return
end
nums.each_with_index do |num, i|
next if used[i]
curr_result << num
used[i] = true
permute_recur(nums, final_result, curr_result, used)
used[i] = false
curr_result.pop
end
end