Kaprekar's Routine — Solution & Editorial
Direct simulation; the routine converges within 7 steps for every valid input.
Complexity: O(1)
Watch out: Keep the 4-digit zero padding during every step — 999 becomes 0999, not 999.
Direct simulation; the routine converges within 7 steps for every valid input.
Complexity: O(1)
Watch out: Keep the 4-digit zero padding during every step — 999 becomes 0999, not 999.