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// 2663. Lexicographically Smallest Beautiful String
#include "leetcode.h"
/*
* a string is beautiful if it consists of the first 'k' letters of the english
* lowercase alphabet, it does not contain a palindrome of length 2 or more
* which is a palindrome. you are given a beautiful string 's' of length 'n',
* and a positive integer 'k'. return the lexicographically smallest string of
* length 'n' which is larger than 's', and is beautiful. if there is no such
* string, return an empty string.
*/
char *smallestBeautifulString(char *s, int k) {
int n = strlen(s);
char *ans = (char *)malloc((n + 1) * sizeof(char));
strcpy(ans, s);
for (int i = n - 1; i >= 0; i--) {
for (int j = ans[i] - 'a' + 1; j < k; j++) {
char curr = j + 'a';
if ((i < 1 || curr != ans[i - 1]) && (i < 2 || curr != ans[i - 2])) {
ans[i] = curr;
for (int l = i + 1; l < n; l++) {
for (int m = 0; m < k; m++) {
curr = m + 'a';
if ((l < 1 || curr != ans[l - 1]) &&
(l < 2 || curr != ans[l - 2])) {
ans[l] = curr;
break;
}
}
}
return ans;
}
}
}
return "";
}
int main() {
char *s1 = "abcz", *s2 = "dc";
char *sbs1 = smallestBeautifulString(s1, 26);
char *sbs2 = smallestBeautifulString(s2, 4);
printf("%s\n", sbs1); // expect: abda
printf("%s\n", sbs2); // expect: null
free(sbs1);
free(sbs2);
}
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