Given a string str of lower case English alphabets. One can choose any two characters in the string and replace all the occurrences of the first character with the second character and replace all the occurrences of the second character with the first character. Find the lexicographically smallest string that can be obtained by doing this operation at most once.
Input: str = “ccad”
Swap all the occurrences of ‘c’ with ‘a’ and all the
occurrences of ‘a’ with ‘c’ to get “aacd” which is the
lexicographically smallest string that we can get.
Input: str = “abba”
The only possible operation will convert the given string
to “baab” which is not lexicographically smallest.
- First we store the first appearance of every character in a string in a hash array chk.
- The in order to find the lexicographically smaller string, the leftmost character must be replaced with some character which is smaller than it. This will only happen if the smaller character appears after it in the array.
- So, starting traversing the string from the left and for every character, find the smallest character (even smaller than the current character) that appears after swap all of their occurrences to get the required string.
- If no such character pair is found in the previous string then print the given string as it is the smallest string possible.
- Lexicographically smallest string formed by appending a character from the first K characters of a given string
- Lexicographically smallest string formed by appending a character from first K characters of a string | Set 2
- Lexicographically smallest substring with maximum occurrences containing a's and b's only
- Make lexicographically smallest palindrome by substituting missing characters
- Lexicographically smallest string whose hamming distance from given string is exactly K
- Lexicographically smallest string of length N and sum K
- Swap characters in a String
- Lexicographically smallest permutation of a string with given subsequences
- K-th lexicographically smallest unique substring of a given string
- Find lexicographically smallest string in at most one swaps
- Queries to answer the X-th smallest sub-string lexicographically
- Lexicographically largest string formed from the characters in range L and R
- Lexicographically smallest string obtained after concatenating array
- Lexicographically smallest string formed by removing at most one character
- Find the lexicographically smallest string which satisfies the given condition
Below is the implementation of the above approach:
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