Given a binary string S of length N, the task is to find the smallest string possible by removing all occurrences of substrings “01” and “11”. After removal of any substring, concatenate the remaining parts of the string.
Input: S = “1010”
Explanation: Removal of substring “01” modifies string S to “10”.
Input: S = “111”
Spac-Optimized Approach: The above approach can be space-optimized by only storing the length of the characters not removed. Follow the steps below to solve the problem:
- Initialize a variable, say st as 0, to store the length of the smallest string possible.
- Iterate over the characters of the string S and perform the following steps:
- If st is greater than 0 and S[i] is equal to ‘1‘, then pop the last element by decrementing st by 1.
- Otherwise, increment st by 1.
- Finally, after completing the above steps, print the answer obtained in st.
Below is the implementation of the above approach:
Time Complexity: O(N)
Auxiliary Space: O(1)
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