1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
|
// 2370. Longest Ideal Subsequence
#include "leetcode.h"
/*
* given a string 's' consisting of lowercase letters and an integer 'k', we
* call a string 't' ideal if the following conditions are satisfied. 't' is a
* subsequence of the string 's'. the absolute difference in the alphabet order
* of every two adjacent letters in 't' is less than or equal to 'k'. return the
* length of the longest ideal sting. a subsequence is a string that can be
* derived from another string by deleting some or no characters without
* changing the order of the remaining characters. note that the alphabet order
* is not cyclic. for example, the absolute difference in the alphabet order of
* 'a' and 'z' is 25, not 1.
*/
int longestIdealString(char *s, int k) {
int n = strlen(s), ans = 0;
int *dp = (int *)malloc(n * sizeof(int));
int *prev = (int *)malloc(26 * sizeof(int));
for (int i = 0; i < n; i++)
dp[i] = 1;
for (int i = 0; i < 26; i++)
prev[i] = -1;
for (int i = 0; i < n; i++) {
for (int j = fmax(0, s[i] - 'a' - k); j <= fmin(25, s[i] - 'a' + k); j++)
if (prev[j] != -1)
dp[i] = fmax(dp[i], 1 + dp[prev[j]]);
prev[s[i] - 'a'] = i;
ans = fmax(ans, dp[i]);
}
return ans;
}
int main() {
char *s1 = "acfgbd", *s2 = "abcd";
printf("%d\n", longestIdealString(s1, 2)); // expect: 4
printf("%d\n", longestIdealString(s2, 4)); // expect: 4
}
|