From 01afc1463a2179b558927a401ec6de803a831c36 Mon Sep 17 00:00:00 2001 From: Chong Jing Hong Date: Wed, 11 Jan 2023 14:25:53 +0800 Subject: [PATCH] Add Java solution to 1930 Unique 3 Length Palindromic Subsequences --- ...que-3-length-palindromic-subsequences.java | 32 +++++++++++++++++++ 1 file changed, 32 insertions(+) create mode 100644 java/1930-unique-3-length-palindromic-subsequences.java diff --git a/java/1930-unique-3-length-palindromic-subsequences.java b/java/1930-unique-3-length-palindromic-subsequences.java new file mode 100644 index 000000000..b2558674f --- /dev/null +++ b/java/1930-unique-3-length-palindromic-subsequences.java @@ -0,0 +1,32 @@ +class Solution { + public int countPalindromicSubsequence(String s) { + char[] letters = new char[]{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', + 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', + 'w', 'x', 'y', 'z'}; + Set left = new HashSet<>(); + Map right = new HashMap<>(); + for(char c : s.toCharArray()) { + right.put(c, right.getOrDefault(c, 0) + 1); + } + Set res = new HashSet<>(); + + for(int mid = 0; mid < s.length(); mid++) { + char c = s.charAt(mid); + + right.put(c, right.get(c)-1); + if(right.get(c) == 0) { + right.remove(c); + } + + for(int i=0; i<26; i++) { + if(left.contains(letters[i]) && right.containsKey(letters[i])) { + res.add("" + letters[i] + c + letters[i]); + } + } + + left.add(c); + } + + return res.size(); + } +} \ No newline at end of file pFad - Phonifier reborn

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