LeetCode-in-Java
1542. Find Longest Awesome Substring
Hard
You are given a string s. An awesome substring is a non-empty substring of s such that we can make any number of swaps in order to make it a palindrome.
Return the length of the maximum length awesome substring of s.
Example 1:
Input: s = “3242415”
Output: 5
Explanation: “24241” is the longest awesome substring, we can form the palindrome “24142” with some swaps.
Example 2:
Input: s = “12345678”
Output: 1
Example 3:
Input: s = “213123”
Output: 6
Explanation: “213123” is the longest awesome substring, we can form the palindrome “231132” with some swaps.
Constraints:
1 <= s.length <= 105sconsists only of digits.
Solution
import java.util.Arrays;
public class Solution {
public int longestAwesome(String s) {
int n = s.length();
int[] idx = new int[(int) Math.pow(2, 10)];
Arrays.fill(idx, Integer.MAX_VALUE);
idx[0] = -1;
int mask = 0;
int ans = 0;
for (int i = 0; i < n; i++) {
mask ^= 1 << (s.charAt(i) - '0');
ans = Math.max(ans, i - idx[mask]);
for (int j = 0; j < 10; j++) {
ans = Math.max(ans, i - idx[mask ^ (1 << j)]);
}
idx[mask] = Math.min(idx[mask], i);
}
return ans;
}
}