Medium

Quiz

#556 Next Greater Element III

APPROACH

Given a positive integer n, find the smallest integer which has exactly the same digits existing in the integer n and is greater in value than n. If no such positive integer exists, return -1.

Note that the returned integer should fit in 32-bit integer, if there is a valid answer but it does not fit in 32-bit integer, return -1.

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?