Given a non-negative number num. The problem is to apply at most one swap operation on the number num so that the resultant is the largest possible number. The number could be very large so a string type can be used to store the number.
Input : n = 8725634 Output : 8765234 Swapped the digits 2 and 6. Input : n = 54321 Output : 54321 No swapping of digits required.
Create an array rightMax. rightMax[i] contains the index of the greatest digit which is on the right side of num[i] and also greater than num[i]. If no such digit exists then rightMax[i] = -1. Now, traverse the rightMax array from i = 0 to n-1(where n is the total number of digits in num), and find the first element having rightMax[i] != -1. Perform the swap(num[i], num[rightMax[i]]) operation and break.
Largest number: 8765234
Time Complexity: O(n), where n is the total number of digits.
Auxiliary Space: O(n), where n is the total number of digits.
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