标签：style blog io ar color sp for on div
Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring.
Analysis:
We define the state d[i][j] as whether S[j-i+1...j] is palindromic, i.e., i is length, j the end of the substring.
d[i][j] is true, only when the char S[j-i+1]==S[j] and S[j-i+1...j-1] is palindromic, i.e., d[i-2][j-1] is true.
NOTE: the function substring() is time consuming.
Solution:
1 public class Solution { 2 public String longestPalindrome(String s) { 3 if (s.length()==0 || s.length()==1) return s; 4 String res = ""; 5 boolean[][] valid = new boolean[s.length()+1][s.length()]; 6 Arrays.fill(valid[0],true); 7 Arrays.fill(valid[1],true); 8 int start = 0, end = 0; 9 for (int i=2;i<=s.length();i++) 10 for (int j=i-1;j<s.length();j++) 11 if (valid[i-2][j-1] && s.charAt(j-i+1)==s.charAt(j)){ 12 valid[i][j]=true; 13 //res = s.substring(j-i+1,j+1); 14 start = j-i+1; 15 end = j+1; 16 } else valid[i][j]=false; 17 18 return s.substring(start,end); 19 } 20 }
Leetcode-Longest Palindromic Substring
标签：style blog io ar color sp for on div
原文地址：http://www.cnblogs.com/lishiblog/p/4125533.html
