Given a string str which contains only the characters x and y, the task is to count all the sub-strings that start and end with an x and have at least a single y.
Input: str = “xyyxx”
“xyyx” and “xyyxx” are the only valid sub-strings.
Input: str = “xyy”
- Create an array countX where countX[i] stores the total x from i to n – 1.
- Now, for every x in the string, find the first y that appears after this x.
- And update count = count + countX[indexOf(y)] because with this x as the starting index, all sub-strings will be valid that will end at any x after the found y.
- Return the count in the end.
Below is the implementation of the above approach:
- Different substrings in a string that start and end with given strings
- Count substrings that starts with character X and ends with character Y
- Given a binary string, count number of substrings that start and end with 1.
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- Count substrings with each character occurring at most k times
- Print Kth character in sorted concatenated substrings of a string
- Replace every character of string by character whose ASCII value is K times more than it
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- Longest Common Prefix using Character by Character Matching
- Replace every character of a string by a different character
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- Print all Subsequences of String which Start with Vowel and End with Consonant.
- Minimum steps to reach end from start by performing multiplication and mod operations with array elements
- Check if frequency of character in one string is a factor or multiple of frequency of same character in other string
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