LeetCode //C - 5. Longest Palindromic Substring

5. Longest Palindromic Substring

Given a string s, return the longest palindromicsubstring in s.

Example 1:

Input: s = "babad"
Output: "bab"
Explanation: "aba" is also a valid answer.

Example 2:

Input: s = "cbbd"
Output: "bb"

Constraints:
  • 1 <= s.length <= 1000
  • s consist of only digits and English letters.

From: LeetCode

Link: 5. Longest Palindromic Substring


Solution:

Ideas:
  1. Expand Around Center: We'll create a helper function, expandFromCenter, to find the length of the palindrome by expanding around its center. This function will handle both odd and even length palindromes.

  2. Iterate Over the String: For each character in the string, we'll use expandFromCenter to check for the longest palindrome centered at that character.

  3. Update the Longest Palindrome: We'll keep track of the longest palindrome we've found so far.

  4. Return the Longest Palindrome: We'll use dynamic memory allocation to create a substring for the longest palindrome and return it.

Code:
c 复制代码
// Helper function to expand from the center and find palindrome length
int expandFromCenter(char* s, int left, int right) {
    while (left >= 0 && right < strlen(s) && s[left] == s[right]) {
        left--;
        right++;
    }
    return right - left - 1;
}

char* longestPalindrome(char* s) {
    if (s == NULL || strlen(s) < 1) return "";

    int start = 0, end = 0;
    for (int i = 0; i < strlen(s); i++) {
        int len1 = expandFromCenter(s, i, i); // Odd length palindromes
        int len2 = expandFromCenter(s, i, i + 1); // Even length palindromes
        int len = len1 > len2 ? len1 : len2;

        if (len > end - start) {
            start = i - (len - 1) / 2;
            end = i + len / 2;
        }
    }

    char* result = malloc(end - start + 2);
    strncpy(result, s + start, end - start + 1);
    result[end - start + 1] = '\0';
    return result;
}
相关推荐
shaun20018 分钟前
华为c编程规范
c语言
MeshddY33 分钟前
(超详细)数据库项目初体验:使用C语言连接数据库完成短地址服务(本地运行版)
c语言·数据库·单片机
森焱森1 小时前
无人机三轴稳定化控制(1)____飞机的稳定控制逻辑
c语言·单片机·算法·无人机
循环过三天1 小时前
3-1 PID算法改进(积分部分)
笔记·stm32·单片机·学习·算法·pid
闪电麦坤951 小时前
数据结构:二维数组(2D Arrays)
数据结构·算法
凌肖战2 小时前
力扣网C语言编程题:快慢指针来解决 “寻找重复数”
c语言·算法·leetcode
埃菲尔铁塔_CV算法2 小时前
基于 TOF 图像高频信息恢复 RGB 图像的原理、应用与实现
人工智能·深度学习·数码相机·算法·目标检测·计算机视觉
NAGNIP3 小时前
一文搞懂FlashAttention怎么提升速度的?
人工智能·算法
Codebee3 小时前
OneCode图生代码技术深度解析:从可视化设计到注解驱动实现的全链路架构
css·人工智能·算法