NeetCode #114LC-1930MediumArrays & Hashing
← Back to All Problems#114 · #1930 · Unique Length-3 Palindromic Subsequences(长度为 3 的不同回文子序列)
📌 Problem Statement & Constraints
Given a string
s, return the number of unique palindromic subsequences of length 3. A subsequence is formed by deleting characters without reordering. Constraints: 3 <= s.length <= 10^5, lowercase letters.🔒
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