# Leetcode: Previous Permutation With One Swap

Previous Permutation With One Swap

Similar Problems:

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. 1 <= A.length <= 10000
2. 1 <= A[i] <= 10000

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

• Solution: XXX

General Thinkings:

```
```

Key Observations:

```
```

Walk Through Testdata

```
```
```// Blog link: https://code.dennyzhang.com/previous-permutation-with-one-swap

```

Share It, If You Like It.