loop from the end of given number till you get a digit less than the previously scanned digit.Let the index of that number be 'i' .
if index = -1,then the given number is the largest one else do the following 1) swap the digit at the index i with the digit just greater than it in the scanned portion 2) sort the remaining scanned digits after index i. Ex:- let the given number be 51432 the digit '1' is the first digit less that its previously scanned digit '4' thus, we swap 2 which is the smallest greater digit the '1' in scanned portion to get 52431 and the we sort the remaining digits after the index to get 52134. --
