使用C語(yǔ)言實(shí)現(xiàn)最長(zhǎng)回文子串的查找

下面是一個(gè)使用C語(yǔ)言實(shí)現(xiàn)查找最長(zhǎng)回文子串的例子：

#include <stdio.h>
#include <string.h>

int expandAroundCenter(char *s, int left, int right) {
    int len = strlen(s);
    while (left >= 0 && right < len && 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 = expandAroundCenter(s, i, i);
        int len2 = expandAroundCenter(s, i, i + 1);
        int len = len1 > len2 ? len1 : len2;
        
        if (len > end - start) {
            start = i - (len - 1) / 2;
            end = i + len / 2;
        }
    }
    
    char *result = (char *)malloc((end - start + 2) * sizeof(char));
    strncpy(result, s + start, end - start + 1);
    result[end - start + 1] = '\0';
    
    return result;
}

int main() {
    char *s = "babad";
    char *result = longestPalindrome(s);
    printf("Longest Palindromic Substring: %s\n", result);
    
    free(result);
    
    return 0;
}

在上面的代碼中，我們定義了一個(gè)expandAroundCenter函數(shù)來(lái)查找以某個(gè)中心展開的回文子串的長(zhǎng)度。然后我們遍歷字符串s，以每個(gè)字符為中心向兩邊擴(kuò)展，分別計(jì)算出奇數(shù)長(zhǎng)度和偶數(shù)長(zhǎng)度的回文子串的長(zhǎng)度，找出最長(zhǎng)的回文子串并返回。最后在main函數(shù)中調(diào)用longestPalindrome函數(shù)來(lái)查找最長(zhǎng)的回文子串并輸出結(jié)果。