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Formatted question description: https://leetcode.ca/all/1332.html
1332. Remove Palindromic Subsequences (Easy)
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.
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: String is already palindrome
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".
Example 4:
Input: s = "" Output: 0
Constraints:
0 <= s.length <= 1000
s
only consists of letters 'a' and 'b'
Related Topics:
String
Solution 1.
// OJ: https://leetcode.com/problems/remove-palindromic-subsequences/
// Time: O(N)
// Space: O(1)
class Solution {
public:
int removePalindromeSub(string s) {
if (s.empty()) return 0;
bool isPalindrome = true;
for (int i = 0, j = s.size() - 1; i < j && isPalindrome; ++i, --j) {
isPalindrome = s[i] == s[j];
}
return isPalindrome ? 1 : 2;
}
};
Java
-
class Solution { public int removePalindromeSub(String s) { if (s == null || s.length() == 0) return 0; int low = 0, high = s.length() - 1; while (low < high) { if (s.charAt(low) == s.charAt(high)) { low++; high--; } else return 2; } return 1; } }
-
// OJ: https://leetcode.com/problems/remove-palindromic-subsequences/ // Time: O(N) // Space: O(1) class Solution { public: int removePalindromeSub(string s) { if (s.empty()) return 0; bool isPalindrome = true; for (int i = 0, j = s.size() - 1; i < j && isPalindrome; ++i, --j) { isPalindrome = s[i] == s[j]; } return isPalindrome ? 1 : 2; } };
-
class Solution: def removePalindromeSub(self, s: str) -> int: if not s: return 0 if s[::-1] == s: return 1 return 2