public class Solution
extends Object
1053 - Previous Permutation With One Swap\.
Medium
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** (A _swap_ exchanges the positions of two numbers `arr[i]` and `arr[j]`). If it cannot be done, then return the same array.
**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 <= 104
* 1 <= arr[i] <= 104