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// 2053. Kth Distinct String in an Array
#include "leetcode.h"
/*
* a distinct string is a string that is present only once in an array. given an
* array of strings 'arr' and an integer 'k', return the k'th eldistinct string
* present in 'arr'. if there are fewer than 'k' distinct strings, return an
* empty string "". note the strings are considered in the order in which they
* appear in the array.
*/
typedef struct {
char str[6];
bool distinct;
int pos;
UT_hash_handle hh;
} element;
int cmp_pos(const element *e1, const element *e2) { return e1->pos - e2->pos; }
char *kthDistinct(char **arr, int arrSize, int k) {
element *hash = NULL, *e;
for (size_t i = 0; i < arrSize; i++) {
const char *str = arr[i];
HASH_FIND_STR(hash, str, e);
if (e) {
e->distinct = false;
} else {
e = (element *)malloc(sizeof(*e));
e->distinct = true;
e->pos = i;
strcpy(e->str, str);
HASH_ADD_STR(hash, str, e);
}
}
HASH_SORT(hash, cmp_pos);
char *ans = (char *)malloc(6 * sizeof(char));
*ans = '\0';
int i = 0;
for (e = hash; e; e = e->hh.next)
if (e->distinct)
if (++i == k) {
strcpy(ans, e->str);
break;
}
return ans;
}
int main() {
char *a1[] = {"d", "b", "c", "b", "c", "a"}, *a2[] = {"aaa", "aa", "a"},
*a3[] = {"a", "b", "a"};
printf("%s\n", kthDistinct((char **)a1, ARRAY_SIZE(a1), 2)); // expect: a
printf("%s\n", kthDistinct((char **)a2, ARRAY_SIZE(a2), 1)); // expect: aaa
printf("%s\n", kthDistinct((char **)a3, ARRAY_SIZE(a3), 3)); // expect: null
}
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