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_467.java
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package com.fishercoder.solutions;
public class _467 {
public static class Solution1 {
/**
* A naive solution would definitely result in TLE.
* Since the pattern keeps repeating, DP is the way to go.
* Because the input consists merely of lowercase English letters, we could maintain an array of size 26,
* keep updating this array, counting the substrings that end with this letter, keep updating it with the largest one possible.
* <p>
* Inspired by this: https://discuss.leetcode.com/topic/70658/concise-java-solution-using-dp
*/
public int findSubstringInWraproundString(String p) {
if (p == null || p.isEmpty()) {
return 0;
}
if (p.length() < 2) {
return p.length();
}
int count = 0;
int[] dp = new int[26];
dp[p.charAt(0) - 'a'] = 1;
int len = 1;
for (int i = 1; i < p.length(); i++) {
if (p.charAt(i) - 1 == p.charAt(i - 1) || (p.charAt(i) == 'a' && p.charAt(i - 1) == 'z')) {
len++;
} else {
len = 1;
}
dp[p.charAt(i) - 'a'] = Math.max(len, dp[p.charAt(i) - 'a']);
}
for (int i : dp) {
count += i;
}
return count;
}
}
}