Given an incomplete bracket sequence S. The task is to find the number of closing brackets ‘)’ needed to make it a regular bracket sequence and print the complete bracket sequence. You are allowed to add the brackets only at the end of the given bracket sequence. If it is not possible to complete the bracket sequence, print “IMPOSSIBLE”.
Let us define a regular bracket sequence in the following way:
- Empty string is a regular bracket sequence.
- If s is a regular bracket sequence, then (s) is a regular bracket sequence.
- If s & t are regular bracket sequences, then st is a regular bracket sequence.
Input : str = “(()(()(”
Output : (()(()()))
Explanation : The minimum number of ) needed to make the sequence regular are 3 which are appended at the end.
Input : str = “())(()”
Output : IMPOSSIBLE
We need to add minimal number of closing brackets ‘)’, so we will count the number of unbalanced opening brackets and then we will add that amount of closing brackets. If at any point the number of the closing bracket is greater than the opening bracket then the answer is IMPOSSIBLE.
Below is the implementation of the above approach:
- Find index of closing bracket for a given opening bracket in an expression
- Minimum number of bracket reversals needed to make an expression balanced | Set - 2
- Minimum number of bracket reversals needed to make an expression balanced
- Check if the bracket sequence can be balanced with at most one change in the position of a bracket
- Check if the bracket sequence can be balanced with at most one change in the position of a bracket | Set 2
- Convert an unbalanced bracket sequence to a balanced sequence
- Minimum sum possible of any bracket sequence of length N
- Find the lexicographical next balanced bracket sequence
- Print Bracket Number
- Number of balanced bracket subsequence of length 2 and 4
- Number of balanced bracket expressions that can be formed from a string
- Count the number of currency notes needed
- Minimum number of letters needed to make a total of n
- Least number of manipulations needed to ensure two strings have identical characters
- Minimum number of Appends needed to make a string palindrome
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