Unique Substrings In Wraparound String Problem
Description
LeetCode Problem 467.
We define the string s to be the infinite wraparound string of “abcdefghijklmnopqrstuvwxyz”, so s will look like this:
- “…zabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcd….”.
Given a string p, return the number of unique non-empty substrings of p are present in s.
Example 1:
1
2
3
Input: p = "a"
Output: 1
Explanation: Only the substring "a" of p is in s.
Example 2:
1
2
3
Input: p = "cac"
Output: 2
Explanation: There are two substrings ("a", "c") of p in s.
Example 3:
1
2
3
Input: p = "zab"
Output: 6
Explanation: There are six substrings ("z", "a", "b", "za", "ab", and "zab") of p in s.
Constraints:
- 1 <= p.length <= 10^5
- p consists of lowercase English letters.
Sample C++ Code
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
class Solution {
public:
int findSubstringInWraproundString(string p) {
vector<int> letters(26, 0);
int res = 0, len = 0;
for (int i = 0; i < p.size(); i++) {
int cur = p[i] - 'a';
if (i > 0 && p[i - 1] != (cur + 26 - 1) % 26 + 'a') len = 0;
if (++len > letters[cur]) {
res += len - letters[cur];
letters[cur] = len;
}
}
return res;
}
};