Given a binary string, the task is to find minimum number of characters to be removed from it so that it becomes alternate. A binary string is alternate if there are no two consecutive 0s or 1s.
Input : s = "000111" Output : 4 We need to delete two 0s and two 1s to make string alternate. Input : s = "0000" Output : 3 We need to delete three characters to make it alternate. Input : s = "11111" Output : 4 Input : s = "01010101" Output : 0 Input : s = "101010" Output : 0
This problem has below simple solution.
We traverse string from left to right and compare current character with next character.
- If current and next are different then no need to perform deletion.
- If current and next are same, we need to perform one delete operation to make them alternate.
Below is the implementation of above algorithm.
# Python 3 program to find minimum number
# of characters to be removed to make
# a string alternate.
# Returns count of minimum characters
# to be removed to make s alternate.
result = 0
for i in range(len(s) – 1):
# if two alternating characters
# of string are same
if (s[i] == s[i + 1]):
result += 1 # then need to
# delete a character
# Driver code
if __name__ == “__main__”:
# This code is contributed by ita_c
4 4 0
Time Complexity : O(n) where n is number of characters in input string.
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