LeetCode-in-Java
2609. Find the Longest Balanced Substring of a Binary String
Easy
You are given a binary string s consisting only of zeroes and ones.
A substring of s is considered balanced if all zeroes are before ones and the number of zeroes is equal to the number of ones inside the substring. Notice that the empty substring is considered a balanced substring.
Return the length of the longest balanced substring of s.
A substring is a contiguous sequence of characters within a string.
Example 1:
Input: s = “01000111”
Output: 6
Explanation: The longest balanced substring is “000111”, which has length 6.
Example 2:
Input: s = “00111”
Output: 4
Explanation: The longest balanced substring is “0011”, which has length 4.
Example 3:
Input: s = “111”
Output: 0
Explanation: There is no balanced substring except the empty substring, so the answer is 0.
Constraints:
1 <= s.length <= 50'0' <= s[i] <= '1'
Solution
public class Solution {
public int findTheLongestBalancedSubstring(String s) {
char[] chars = s.toCharArray();
int max = 0;
int n = chars.length;
int zero = 0;
int one = 0;
int i = 0;
while (i < n) {
if (chars[i] == '0') {
zero++;
} else {
while (i < n) {
if (chars[i++] == '1') {
one++;
} else {
i--;
break;
}
}
max = Math.max(max, 2 * Math.min(one, zero));
zero = 1;
one = 0;
}
i++;
}
return max;
}
}