Next Permutation
A permutation of an array of integers is an arrangement of its members into a sequence or linear order.
- For example, for
arr = [1,2,3], the following are considered permutations ofarr:[1,2,3],[1,3,2],[3,1,2],[2,3,1].
The next permutation of an array of integers is the next lexicographically greater permutation of its integer. More formally, if all the permutations of the array are sorted in one container according to their lexicographical order, then the next permutation of that array is the permutation that follows it in the sorted container. If such arrangement is not possible, the array must be rearranged as the lowest possible order (i.e., sorted in ascending order).
- For example, the next permutation of
arr = [1,2,3]is[1,3,2]. - Similarly, the next permutation of
arr = [2,3,1]is[3,1,2]. - While the next permutation of
arr = [3,2,1]is[1,2,3]because[3,2,1]does not have a lexicographical larger rearrangement.
Given an array of integers nums, find the next permutation of nums.
The replacement must be in place and use only constant extra memory.
Example 1:
Input: nums = [1,2,3]
Output: [1,3,2]To understand this problem better, Let us take an example of word (alphabets)
Suppose there is word “ABCDE”, and if we want next permutation of that word. Next word in dictionary then we will go from the right side of word.
2nd permutation
ABCDE -> E is larger than D, swap E and D
3rd permutation
If we have give 2nd row as word and want next permutations then we will traverse from right to left:
D is lower than E, move to next pair
E is larger than C, so we need to swap pair.
For that we need to find which alphabet is larger than C character but larger than after C character, which is D so we swap D with C. After that we’ll sort after C characters.
Same goes with number thing :
swapping is the key in this problem
That’s it for the today. If you have any doubt, feel free to raise query via comment section.
