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https://github.com/TheAlgorithms/C
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feat: add Longest Palindrome Substring solution (#1210)
* feat: add Longest Palindrome Substring solution * fix: update formatting and allocate new results string * fix: update formatting, fix bug related to the string copy * fix: add parantheses for one line if statement * fix: add comments for library inclusions
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| 2 | [Add Two Numbers](https://leetcode.com/problems/add-two-numbers) | [C](./src/2.c) | Medium |
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| 3 | [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters) | [C](./src/3.c) | Medium |
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| 4 | [Median of Two Sorted Arrays](https://leetcode.com/problems/median-of-two-sorted-arrays) | [C](./src/4.c) | Hard |
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| 5 | [Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring) | [C](./src/5.c) | Medium |
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| 6 | [Zigzag Conversion](https://leetcode.com/problems/zigzag-conversion) | [C](./src/6.c) | Medium |
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| 7 | [Reverse Integer](https://leetcode.com/problems/reverse-integer) | [C](./src/7.c) | Medium |
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| 8 | [String to Integer (atoi)](https://leetcode.com/problems/string-to-integer-atoi) | [C](./src/8.c) | Medium |
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leetcode/src/5.c
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leetcode/src/5.c
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/**
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* Find longest palindrome by traversing the string and checking how
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* long palindrome can be constructed from each element by going left and right.
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* Checking palindromes of types '..aa..' and '..bab..'
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*/
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#include <stdlib.h> /// for allocating new string via malloc()
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#include <string.h> /// for copying the contents of the string via strncpy()
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char * longestPalindrome(char * s) {
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int si_max = 0, ei_max = 0, sz_max = 0, sz, i, delta_i;
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char ch, *s_longest;
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if (s[1] == '\0') return s;
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for (ch = s[1], i = 1; ch != '\0'; ch = s[++i]) {
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if (s[i - 1] == ch) {
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sz = 2;
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delta_i = 1;
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while (i - 1 - delta_i >= 0 && s[i + delta_i] != '\0' && s[i - 1 - delta_i] == s[i + delta_i]) {
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sz += 2;
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delta_i += 1;
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}
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if (sz > sz_max) {
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sz_max = sz;
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si_max = i - 1 - delta_i + 1;
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ei_max = i + delta_i - 1;
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}
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}
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}
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for (ch = s[0], i = 1; ch != '\0'; ch = s[++i]) {
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sz = 1;
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delta_i = 1;
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while (i - delta_i >= 0 && s[i + delta_i] != '\0' && s[i - delta_i] == s[i + delta_i]) {
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sz += 2;
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delta_i += 1;
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}
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if (sz > sz_max) {
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sz_max = sz;
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si_max = i - delta_i + 1;
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ei_max = i + delta_i - 1;
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}
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}
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if ((s_longest = (char *) malloc(sizeof(s))) == NULL) {
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return NULL;
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}
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strncpy(s_longest, s + si_max, sz_max);
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s_longest[sz_max] = '\0';
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return s_longest;
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}
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