// 5. Longest Palindromic Substring #include "leetcode.h" /* * given a string 's', return the longest palindromic substring in 's' */ char *longestPalindrome(char *s) { char *start, *end, *p = s, *sub_start = s; int max_len = 1; while (*p) { start = p; end = p; while (*(end + 1) && *(end + 1) == *end) end++; p = end + 1; while (*(end + 1) && (start > s) && *(end + 1) == *(start - 1)) { start--; end++; } if (end - start + 1 > max_len) { max_len = end - start + 1; sub_start = start; } } char *ans = (char *)calloc(max_len + 1, sizeof(char)); strncpy(ans, sub_start, max_len); return ans; } int main() { char s1[] = {"babad"}, s2[] = {"cbbd"}; printf("%s\n", longestPalindrome(s1)); // expect: bab printf("%s\n", longestPalindrome(s2)); // expect: bb }