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feat: 5_longest_palindromic_substring

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SquidSpirit 2025-02-13 23:08:55 +08:00
parent 3284c1e532
commit 95f023f12a
1 changed files with 59 additions and 0 deletions
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5_longest_palindromic_substring/main.cpp Normal file
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#include <bits/stdc++.h>
using namespace std;
class Solution {
public:
int findPalindromeLength(const string &str, int center, int skip) {
for (int radius = skip; center - radius >= 0 && center + radius < str.length(); radius++) {
char r = str[center + radius];
char l = str[center - radius];
if (r != l) {
return radius - 1;
}
}
return min(center, (int)str.length() - 1 - center);
}
string longestPalindrome(string s) {
string str = "#";
for (auto c : s) {
str.push_back(c);
str.push_back('#');
}
vector<int> p(str.length(), 0);
int center = 0, right = 0, maxRadius = 0;
for (int index = 1; index < str.length() - 1; index++) {
if (index > right) {
int radius = findPalindromeLength(str, index, 1);
p[index] = radius;
if (radius >= maxRadius) {
maxRadius = radius;
center = index;
right = center + radius;
}
continue;
}
int indexMirror = center - (index - center);
if (index + p[indexMirror] < right) {
p[index] = p[indexMirror];
continue;
}
int radius = findPalindromeLength(str, index, right - index);
p[index] = radius;
if (radius >= maxRadius) {
maxRadius = radius;
center = index;
right = center + radius;
}
}
int start = (center - maxRadius) / 2;
int length = maxRadius;
return s.substr(start, length);
}
};