文章目录
一、题目
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' <= si <= '1'
二、题解
cpp
class Solution {
public:
int findTheLongestBalancedSubstring(string s) {
int n = s.length();
int res = 0;
for(int i = 0;i < n;i++){
//过滤到字符串最前面的1
if(s[i] - '0' == 1) continue;
int zeroCount = 0;
int oneCount = 0;
//统计0的数量
while(s[i] - '0' == 0 && i < n) zeroCount++,i++;
//统计1的数量
while(s[i] - '0' == 1 && i < n) oneCount++,i++;
i--;
res = max(res,min(zeroCount,oneCount) * 2);
}
return res;
}
};