Given a string str containing only characters x and y, the task is to perform the following operations while possible:
Find an index such that s[i] = ‘x’ and s[i+1] = ‘y’ and delete both the characters s[i] and s[i+1], if no such index is found then find an index such that s[i] = ‘y’ and s[i+1] = ‘x’ and swap(s[i], s[i+1]).
Print the final string after performing the given operation.
Input: str = “xyyxx”
Step 1: yxx (xy got deleted)
Step 2: xyx (yx got swapped)
Step 3: x (xy got deleted)
Input: str = “xxyyxyy”
Approach: In the final string there will be either only x or only y because if we have both x and y in the string then there would be a point where we have either xy or yx as sub-string.
- If it’s xy, we delete it straight away.
- If it is yx, we reverse it to get xy and then delete it.
Since in each deletion step, one x and one y gets deleted, the final string would have min(x, y) number of x and y characters deleted.
Below is the implementation of the above approach:
# Python 3 implementation of the approach
# Function to return the modified string
i, n = 0, 0
n = len(s)
x, y = 0, 0
for i in range(0, n):
# Count number of ‘x’
if (s[i] == ‘x’):
x += 1
# Count number of ‘y’
y += 1
finalString = “”
# min(x, y) number of ‘x’ and
# ‘y’ will be deleted
if (x > y):
for i in range(0, x – y):
finalString += “x”
for i in range(0, y – x):
finalString += “y”
# Driver Code
if __name__ == ‘__main__’:
s = “xxyyxyy”
# This code contributed by 29AjayKumar
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