Find next greater number with same set of digits!!

// C++ program to find the smallest number which greater than a given number
// and has same set of digits as given number
#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;

// Utility function to swap two digits
void swap(char *a, char *b)
{
char temp = *a;
*a = *b;
*b = temp;
}

// Given a number as a char array number[], this function finds the
// next greater number. It modifies the same array to store the result
void findNext(char number[], int n)
{
int i, j;

// I) Start from the right most digit and find the first digit that is
// smaller than the digit next to it.
for (i = n-1; i > 0; i--)
if (number[i] > number[i-1])
break;

// If no such digit is found, then all digits are in descending order
// means there cannot be a greater number with same set of digits
if (i==0)
{
cout << "Next number is not possible";
return;
}

// II) Find the smallest digit on right side of (i-1)'th digit that is
// greater than number[i-1]
int x = number[i-1], smallest = i;
for (j = i+1; j < n; j++)
if (number[j] > x && number[j] < number[smallest])
smallest = j;

// III) Swap the above found smallest digit with number[i-1]
swap(&number[smallest], &number[i-1]);

// IV) Sort the digits after (i-1) in ascending order
sort(number + i, number + n);

cout << "Next number with same set of digits is " << number;

return;
}

// Driver program to test above function
int main()
{
char digits[] = "534976";
int n = strlen(digits);
findNext(digits, n);
return 0;
}