Medium

Quiz

#556 Next Greater Element III

APPROACH

Given a positive integer n, find the smallest integer that uses exactly the same set of digits as n but has a greater value. Return -1 if no such integer exists, or if the answer would exceed the 32-bit signed integer range.

Example 1:

Input: n = 12

Output: 21

Example 2:

Input: n = 21

Output: -1

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What is the optimal approach for this problem?