PROBLEM LINK:Author: ravikiran0606 DIFFICULTY:EASYMEDIUM PREREQUISITES:RECURSION, BACKTRACKING PROBLEM:Given an integer N and a string S of length N. We need to generate a number with N+1 digits such that the following contraints holds true, 1) If the (i)'th character of the string is I, then (i)'th digit in the number > (i+1)'th digit in that number. EXPLANATION:In this question, its very easy to find one of the cases for 1 that for all N>=9, the answer is always 1 since there are only 9 nonzero distinct digits from 1 to 9. Thus we can find solution only if N<=8. If the length of the string is N, we need to generate a number with N+1 digits with the given contraint. We can solve this using recursion and backtracking by trying all possible combinations of digits of length N+1 with the given constraint and print the lexicographically smallest one. If no solution exists we can print 1. The expected complexity is O(9^{n}). AUTHOR'S SOLUTION:Author's solution can be found here asked 13 Mar, 19:36
