Given a string S consisting of lowercase alphabets. The task is to find the lexicographically smallest string X of the same length only that can be formed using the operation given below:
In a single operation, select any one character among the at most first K characters of string S, remove it from string S and append it to string X. Apply this operation as many times as he wants.
Input: str = “gaurang”, k=3
Remove ‘a’ in the first step and append to X.
Remove ‘g’ in the second step and append to X.
Remove ‘a’ in the third step and append to X.
Remove ‘n’ in the third step and append to X.
Pick the lexicographically smallest character at every step from the first K characters to get the
Input: str = “geeksforgeeks”, k=5
- Find the smallest character in the first k characters in the string S.
- Delete the smallest character found from the string.
- Append the smallest character found to the new string X.
- Repeat the above steps till the string s is empty.
Below is the implementation of the above approach:
# Python 3 program to find the new string
# after performing deletions and append
# operation in the string s
# Function to find the new string thus
# formed by removing characters
def newString(s, k):
# new string
X = “”
# Remove characters until
# the string is empty
while (len(s) > 0):
temp = s
# Traverse to find the smallest
# character in the first k characters
i = 1
while(i < k and i < len(s)): if (s[i] < temp): temp = s[i] i += 1 # append the smallest character X = X + temp # removing the lexicographically # smallest character from the string for i in range(k): if (s[i] == temp): s = s[0:i] + s[i + 1:] break return X # Driver Code if __name__ == '__main__': s = "gaurang" k = 3 print(newString(s, k)) # This code is contributed by # Shashank_Sharma [tabby title="C#"]
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