Watch 10 video solutions for Previous Permutation With One Swap, a medium level problem involving Array, Greedy. This walkthrough by NeetCode has 390,029 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
Given an array of positive integers arr (not necessarily distinct), return the lexicographically largest permutation that is smaller than arr, that can be made with exactly one swap. If it cannot be done, then return the same array.
Note that a swap exchanges the positions of two numbers arr[i] and arr[j]
Example 1:
Input: arr = [3,2,1] Output: [3,1,2] Explanation: Swapping 2 and 1.
Example 2:
Input: arr = [1,1,5] Output: [1,1,5] Explanation: This is already the smallest permutation.
Example 3:
Input: arr = [1,9,4,6,7] Output: [1,7,4,6,9] Explanation: Swapping 9 and 7.
Constraints:
1 <= arr.length <= 1041 <= arr[i] <= 104