52 lines
1.4 KiB
C++
52 lines
1.4 KiB
C++
// Source : https://leetcode.com/problems/palindromic-substrings/
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// Author : Hao Chen
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// Date : 2019-01-30
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/*****************************************************************************************************
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*
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*
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* Given a string, your task is to count how many palindromic substrings in this string.
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*
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* The substrings with different start indexes or end indexes are counted as different substrings even
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* they consist of same characters.
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*
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* Example 1:
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*
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* Input: "abc"
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* Output: 3
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* Explanation: Three palindromic strings: "a", "b", "c".
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*
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* Example 2:
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*
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* Input: "aaa"
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* Output: 6
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* Explanation: Six palindromic strings: "a", "a", "a", "aa", "aa", "aaa".
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*
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* Note:
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*
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* The input string length won't exceed 1000.
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*
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******************************************************************************************************/
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class Solution {
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public:
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int countSubstrings(string s) {
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int len = s.size();
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if (len<=1) return len;
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vector< vector<bool> > dp(len, vector<bool>(len, false));
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int cnt = 0;
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for( int i=len-1; i>=0; i--) {
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for (int j=i; j<=len-1; j++) {
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if ( i == j || ( s[i] == s[j] && ( j-i<2 || dp[i+1][j-1]) ) ) {
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dp[i][j] = true;
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cnt++;
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}
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}
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}
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return cnt;
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}
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};
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