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| // @Title: 最长回文子串 (Longest Palindromic Substring)
// @Author: 15816537946@163.com
// @Date: 2020-10-24 11:49:01
// @Runtime: 4 ms
// @Memory: 2.1 MB
impl Solution {
fn expand_center(s: &[char], left: usize, mut right: usize) -> isize {
let mut left = left as isize;
while left >= 0 && right < s.len() && s[left as usize] == s[right] {
left -= 1;
right += 1;
}
right as isize - left as isize - 1
}
pub fn longest_palindrome(s: String) -> String {
let len = s.len();
if len < 2 {
return s;
}
let s: Vec<char> = s.chars().collect();
let mut start = 0;
let mut end = 0;
for i in 0..len {
let len_odd = Solution::expand_center(&s, i, i);
let len_even = Solution::expand_center(&s, i, i + 1);
let max_len = len_odd.max(len_even).max(0) as usize;
if max_len > end - start {
start = i - (max_len - 1) / 2;
end = i + max_len / 2;
}
}
s[start..=end].iter().collect()
}
}
/*
impl Solution {
/*
fn helper(s: &str, l: usize, r: usize) -> isize {
let mut l = l;
let mut r = r;
let str_vec: Vec<char> = s.chars().collect();
while l >= 0 && r < s.len() && str_vec[l] == str_vec[r] {
l -= 1;
r += 1;
}
r as isize - l as isize - 1
}
*/
fn helper(s: &str, left: usize, mut right: usize) -> isize {
let mut left = left as isize;
let str_vec: Vec<char> = s.chars().collect();
while left >= 0 && right < s.len() && str_vec[left as usize] == str_vec[right] {
left -= 1;
right += 1;
}
right as isize - left as isize - 1
}
pub fn longest_palindrome(s: String) -> String {
if s.len() < 2 {
return s;
}
let (mut lo, mut hi) = (0, 0);
for i in 0..s.len() {
let len1 = Solution::helper(&s, i, i);
let len2 = Solution::helper(&s, i, i + 1);
let large = len1.max(len2).max(0) as usize;
if large > hi - lo {
lo = i - (large - 1) >> 1;
hi = i + large >> 1;
}
}
String::from(&s[lo..=hi + 1])
}
}
*/
|