One Swap Away
Can the list be made non-decreasing by swapping at most one pair of elements?
Input: the first line has N; the second line has N integers.
Output: YES or NO.
Constraints:
- 1 ≤ N ≤ 105
- −109 ≤ ai ≤ 109
Sample Tests
Input 1
4 1 4 3 2
Output 1
YES
Input 2
3 3 1 2
Output 2
NO
Discussion (opens after you solve — no spoilers before)
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