Exchange Digits – TCS CodeVita

Compute the nearest larger number by interchanging its digits updated.Given 2 numbers a and b find the smallest number greater than b by interchanging the digits of a and if not possible print -1.

• Input Format
  2 numbers a and b, separated by space.
• Output Format
  A single number greater than b.If not possible, print -1
• Constraints
  1 <= a,b <= 10000000

Example 1:

Sample Input:

    459 500

Sample Output:
    549

Example 2:

Sample Input:

    645757 457765

Sample Output:
    465577

C++
#include <bits/stdc++.h>
using namespace std;
int main()
{
    string a, b;
    cin >> a >> b;
    sort(a.begin(), a.end());
    string temp = a;
    int flag = 1;
    while (stoi(temp) <= stoi(b))
    {
        bool temp1 = next_permutation(a.begin(), a.end());
        temp = a;
        if (!temp1)
        {
            flag = 0;
            break;
        }
    }
    if (flag)
        cout << stoi(a)<<endl;
    else
        cout << "-1n";
    return 0;
}

Python
from itertools import permutations
m = input()
n = input()
lst = sorted([int("".join(char)) for char in permutations(m)])
for i in lst:
if i > int(n):
print(i)
;break