Remove Palindromic Subsequences
You are given a string s consisting only of letters 'a' and 'b'. In a single step you can remove one palindromic subsequence from s.
Return the minimum number of steps to make the given string empty.
A string is a subsequence of a given string if it is generated by deleting some characters of a given string without changing its order. Note that a subsequence does not necessarily need to be contiguous.
A string is called palindrome if is one that reads the same backward as well as forward.
Example 1:
Input: s = "ababa"
Output: 1
Explanation: s is already a palindrome, so its entirety can be removed in a single step.
Example 2:
Input: s = "abb"
Output: 2
Explanation: "abb" -> "bb" -> "".
Remove palindromic subsequence "a" then "bb".
Example 3:
Input: s = "baabb"
Output: 2
Explanation: "baabb" -> "b" -> "".
Remove palindromic subsequence "baab" then "b".
思路一:题目意思理解错了,subsequences 意思是可以不用连续的,结果这题卡了很久。理解正确意思后就好处理了,只有两个字符,删掉其中一个字符就满足提交了。所以判断一下字符串是否是回文,不是回文才需要删除操作,最多需要两次
public int removePalindromeSub(String s) {
char[] chars = s.toCharArray();
return isPalindromic(chars) ? 1 : 2;
}
public boolean isPalindromic(char[] chars) {
int begin = 0;
int end = chars.length - 1;
while (begin < end) {
if (chars[begin++] != chars[end--]) return false;
}
return true;
}
原文地址:http://www.cnblogs.com/iyiluo/p/16833200.html
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