Given an array A of positive integers (not necessarily distinct), return the lexicographically largest permutation that is smaller than A, that can be made with one swap (A swap exchanges the positions of two numbers A[i] and A[j]). If it cannot be done, then return the same array.
Example 1:
Input: [3,2,1]
Output: [3,1,2]
Explanation: Swapping 2 and 1.
Example 2:
Input: [1,1,5]
Output: [1,1,5]
Explanation: This is already the smallest permutation.
Example 3:
Input: [1,9,4,6,7]
Output: [1,7,4,6,9]
Explanation: Swapping 9 and 7.
Example 4:
Input: [3,1,1,3]
Output: [1,3,1,3]
Explanation: Swapping 1 and 3.
Note:
1 <= A.length <= 100001 <= A[i] <= 10000