Using array instead of set<string> - c++

Question

This is a function for finding all Longest common sequence for X and Y sequence.
But this program is in c++ but I want to write it in C.
Is there any way to use array instead of the set?
For eg. if input is
X = < A, A, T, C, C, >
Y = < A, C, A, C, G, >
then the output should be
< A, C, C, >
< A, A, C, >
m and n are size of sequence X and Y respectively.
/* source : https://www.geeksforgeeks.org/printing-longest-common-subsequence-set-2-printing/ */
/* Returns set containing all LCS for X[0..m-1], Y[0..n-1] */
set<string> findLCS(string X, string Y, int m, int n)
{
// construct a set to store possible LCS
set<string> s;
// If we reaches end of either string, return
// a empty set
if (m == 0 || n == 0)
{
s.insert("");
return s;
}
// If the last characters of X and Y are same
if (X[m - 1] == Y[n - 1])
{
// recurse for X[0..m-2] and Y[0..n-2] in
// the matrix
set<string> tmp = findLCS(X, Y, m - 1, n - 1);
// append current character to all possible LCS
// of substring X[0..m-2] and Y[0..n-2].
for (string str : tmp)
s.insert(str + X[m - 1]);
}
// If the last characters of X and Y are not same
else
{
// If LCS can be constructed from top side of
// the matrix, recurse for X[0..m-2] and Y[0..n-1]
if (L[m - 1][n] >= L[m][n - 1])
s = findLCS(X, Y, m - 1, n);
// If LCS can be constructed from left side of
// the matrix, recurse for X[0..m-1] and Y[0..n-2]
if (L[m][n - 1] >= L[m - 1][n])
{
set<string> tmp = findLCS(X, Y, m, n - 1);
// merge two sets if L[m-1][n] == L[m][n-1]
// Note s will be empty if L[m-1][n] != L[m][n-1]
s.insert(tmp.begin(), tmp.end());
}
}
return s;
}

Answer 1

Here is an example for a self-made C unordered_set using arrays.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define Buckets 1000
struct Node {
char *key;
struct Node *next;
};
void initNode(struct Node **node, const char *str) {
*node = (struct Node *) malloc(sizeof(struct Node));
size_t l = strlen(str);
(*node)->key = (char *) malloc(l * sizeof(char));
strncpy((*node)->key, str, l);
(*node)->next = NULL;
}
void freeNode(struct Node *node) {
if (node->next) {
freeNode(node->next);
}
free(node->key);
free(node);
}
struct Set {
struct Node *buckets[Buckets];
};
void initSet(struct Set *set) {
for (unsigned int i = 0; i < Buckets; ++i) {
set->buckets[i] = NULL;
}
}
void freeSet(struct Set *set) {
for (unsigned int i = 0; i < Buckets; ++i) {
if (set->buckets[i]) {
free(set->buckets[i]);
}
}
}
unsigned int hash(const char *str) {
unsigned int sum = 0;
for (; *str; ++str) {
sum += *str;
}
return sum % Buckets;
}
int insert(struct Set *set, const char *str) {
const unsigned int h = hash(str);
if (!set->buckets[h]) {
initNode(&set->buckets[h], str);
return 1;
}
struct Node *node = set->buckets[h];
while (node->next && strcmp(str, node->key)) node = node->next;
if (!strcmp(str, node->key)) return 0;
initNode(&node->next, str);
return 1;
}
int main() {
struct Set set;
initSet(&set);
printf("%d", insert(&set, "Text"));
printf("%d", insert(&set, "Text2"));
printf("%d", insert(&set, "Text"));
freeSet(&set);
}