Re: [閒聊] 每日leetcode

[Rushia (早瀬ユウカの体操服 )]

※ 引述《dont (dont)》之銘言：
: 1930. Unique Length-3 Palindromic Subsequences
思路差不多
找到最左和最右的字母然後檢查中間有幾種字母
本來以為這種解算是滿暴力的但是跑出來還滿快的

java code:
--------------------------------------------------
class Solution {
    public int countPalindromicSubsequence(String s) {
        int res = 0;
        for (char c = 'a'; c <= 'z'; c = (char) (c + 1)) {
            boolean[] words = new boolean[26];
            int l = s.indexOf(c) + 1;
            int r = s.lastIndexOf(c) - 1;
            while (l <= r) {
                words[s.charAt(l++) - 'a'] = true;
            }
            for (boolean word : words) {
                if (word) res++;
            }
        }
        return res;
    }
}
--------------------------------------------------

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