C# 代码
public class Solution {
public int FindTheLongestBalancedSubstring(string s) {
int n = s.Length;
int result = 0;
int prev = 0, cur = 0;
for (int i = 0; i < n; i++){
cur++;
if (i == n - 1 || s[i] != s[i + 1]){
if (s[i] == '1'){
result = Math.Max(result, Math.Min(prev, cur) * 2);
}
prev = cur;
cur = 0;
}
}
return result;
}
}