151 DSA Problem journey

Q7:)Given a positive integer, find the smallest integer that 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 a 32-bit integer, if there is a valid answer but it does not fit in a 32-bit integer, it returns -1.

Example:

>Input: n = 12
Output: 21
>Input: n = 21
Output: -1

Solution:
class Solution {
public:
    int nextGreaterElement(int n) {
    auto digits = to_string(n);
    next_permutation(begin(digits), end(digits));
    auto res = stoll(digits);
    return (res > INT_MAX || res <= n) ? -1 : res;      
    }
};
Explantion:
The given C++ code defines a class Solution with a public method nextGreaterElement. 
This method takes an integer n as input and returns the next greater permutation of its digits. 
If there is no such permutation, it returns -1.

Here's a breakdown of the code:

.)auto digits = to_string(n);:
Convert the integer n to a string, which makes it easier to work with individual digits.

.)next_permutation(begin(digits), end(digits));: 
Rearrange the characters in the digits string to generate the next lexicographically greater permutation. 
This function is part of the C++ Standard Template Library (STL).

.)auto res = stoll(digits);: 
Convert the rearranged string back to an integer using stoll (string to long long).

.)return (res > INT_MAX || res <= n) ? -1 : res;:
Check if the result is greater than the maximum value of an integer (INT_MAX) or if it's less than or equal to the original number n.
If either condition is true, return -1; otherwise, return the result.

.)It's worth noting that this implementation assumes the input n is a 32-bit signed integer.
If the result is outside the range of a 32-bit integer, it returns -1. If there is no greater permutation, 
it also returns -1.

If anyone have better solution so please comment:)