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This approach uses a hash map to store the first and last occurrence of each character as you traverse the string. For each character, calculate the distance between its occurrences and keep track of the maximum distance found. This efficiently provides the length of the longest substring between two identical characters.
Time Complexity: O(n) where n is the length of the string.
Space Complexity: O(1) since the hash map size is constant (fixed at 256 for all possible lowercase characters).
1var maxLengthBetweenEqualCharacters = function(s) {
2 let firstOccurrence = {};
3 let maxLen = -1;
4 for (let i = 0; i < s.length; i++) {
5 if (!(s[i] in firstOccurrence)) {
6 firstOccurrence[s[i]] = i;
7 } else {
8 maxLen = Math.max(maxLen, i - firstOccurrence[s[i]] - 1);
9 }
10 }
11 return maxLen;
12};
13
14console.log(maxLengthBetweenEqualCharacters('abca'));This JavaScript solution uses an object as a hashmap to store the indices of the first occurrence of each character, facilitating a calculation of the desired maximum length for the substring between identical characters.
JavaScript code implements a similar process by using objects for first and last occurrence tracking, performing substring length calculations to determine the largest possible value.