LeetCode 1216. Valid Palindrome III

原题链接在这里：https://leetcode.com/problems/valid-palindrome-iii/

题目：

Given a string s and an integer k, find out if the given string is a K-Palindrome or not.

A string is K-Palindrome if it can be transformed into a palindrome by removing at most k characters from it.

Example 1:

Input: s = "abcdeca", k = 2
Output: true
Explanation: Remove 'b' and 'e' characters.

Constraints:

• 1 <= s.length <= 1000
• s has only lowercase English letters.
• 1 <= k <= s.length

题解：

Find the longest palindrome from s.

And check the difference between s and longest palindrome length, if it is <= k, then return true.

Time Complexity: O(n^2). n = s.length().

Space: O(n^2).

AC Java:

 class Solution {
     public boolean isValidPalindrome(String s, int k) {
         if(s == null || s.length() <= k){
             return true;
         }

         int lp = findLongestPalin(s);
         return s.length() - lp <= k;
     }

     private int findLongestPalin(String s){
         if(s == null || s.length() == 0){
             return 0;
         }

         int n = s.length();
         int [][] dp = new int[n][n];
         for(int i = n-1; i>=0; i--){
             dp[i][i] = 1;
             for(int j = i+1; j<n; j++){
                 if(s.charAt(i) == s.charAt(j)){
                     dp[i][j] = dp[i+1][j-1] + 2;
                 }else{
                     dp[i][j] = Math.max(dp[i+1][j], dp[i][j-1]);
                 }
             }
         }

         return dp[0][n-1];
     }
 }

类似Longest Palindromic Subsequence, Valid Palindrome, Valid Palindrome II.