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LeetCode/#longest-palindromic-substring
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| Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. | |
| Example 1: | |
| Input: "babad" | |
| Output: "bab" | |
| Note: "aba" is also a valid answer. | |
| Example 2: | |
| Input: "cbbd" | |
| Output: "bb" | |
| My code: | |
| import numpy as np | |
| class Solution: | |
| def __init__(self): | |
| self.result = "" | |
| def longestPalindrome(self, s): | |
| """ | |
| :type s: str | |
| :rtype: str | |
| """ | |
| # LCS method | |
| if len(s) <= 1: | |
| return s | |
| self.flag = np.zeros((len(s), len(s))) - 1 | |
| #Init base case | |
| for i in range(len(s)): | |
| self.flag[i,i]=1 | |
| self.str_list = [] | |
| for i in range(len(s)): | |
| tmp_list = [] | |
| for j in range(len(s)): | |
| if i!=j: | |
| tmp_str = "" | |
| else: | |
| tmp_str=s[i] | |
| tmp_list.append(tmp_str) | |
| self.str_list.append(tmp_list) | |
| tmp_Str, tmp_flag = self.Recursive(s, 0, len(s) - 1) | |
| #print(self.flag) | |
| #print(tmp_flag) | |
| #print(tmp_Str) | |
| if len(tmp_Str)==1: | |
| return s[0] | |
| return tmp_Str | |
| def Recursive(self, s1, i, j): | |
| if len(s1) == 1: | |
| return s1, True | |
| if i>j: | |
| return "", 0 | |
| if self.flag[i, j] != -1: | |
| tmp_flag = self.flag[i, j] | |
| tmp_list = self.str_list[i] | |
| tmp_str = tmp_list[j] | |
| return tmp_str, tmp_flag | |
| if s1[i] == s1[j]: | |
| #print("now index i %d index j %d now the result %c"%(i,j,s1[i])) | |
| tmp_str, tmp_flag = self.Recursive(s1, i + 1, j - 1) | |
| if tmp_flag==j-i-1: | |
| self.flag[i, j] = tmp_flag+2 | |
| tmp_str = s1[i]+tmp_str + s1[i] | |
| tmp_list = self.str_list[i] | |
| tmp_list[j] = tmp_str | |
| else: | |
| tmp_str1, tmp_flag1 = self.Recursive(s1, i + 1, j) | |
| tmp_str2, tmp_flag2 = self.Recursive(s1, i, j - 1) | |
| if tmp_flag1 > tmp_flag2: | |
| #print("index i %d index j %d" % (i, j)) | |
| tmp_list = self.str_list[i] | |
| tmp_list[j] = tmp_str1 | |
| self.flag[i, j] = tmp_flag1 | |
| return tmp_str1, tmp_flag1 | |
| else: | |
| tmp_list = self.str_list[i] | |
| tmp_list[j] = tmp_str2 | |
| self.flag[i, j] = tmp_flag2 | |
| return tmp_str2, tmp_flag2 | |
| return tmp_str, self.flag[i,j] | |
| else: | |
| tmp_str1, tmp_flag1 = self.Recursive(s1, i + 1, j) | |
| tmp_str2, tmp_flag2 = self.Recursive(s1, i, j - 1) | |
| if tmp_flag1>tmp_flag2: | |
| #print("index i %d index j %d" % (i, j)) | |
| tmp_list = self.str_list[i] | |
| tmp_list[j] = tmp_str1 | |
| self.flag[i, j] = tmp_flag1 | |
| return tmp_str1, tmp_flag1 | |
| else: | |
| tmp_list = self.str_list[i] | |
| tmp_list[j] = tmp_str2 | |
| self.flag[i, j] = tmp_flag2 | |
| return tmp_str2, tmp_flag2 | |
| Solution: | |
| https://leetcode.com/problems/longest-palindromic-substring/ |