diff --git a/heoh/leetcode-2609.py b/heoh/leetcode-2609.py
new file mode 100644
index 0000000..1890f29
--- /dev/null
+++ b/heoh/leetcode-2609.py
@@ -0,0 +1,23 @@
+class Solution:
+    def findTheLongestBalancedSubstring(self, s: str) -> int:
+        state = '0'
+        n_zeroes = 0
+        n_ones = 0
+        best = 0
+        for c in s:
+            if state == '0':
+                if c == '0':
+                    n_zeroes += 1
+                else:
+                    state = '1'
+                    n_ones += 1
+            else:
+                if c == '0':
+                    n_zeroes = 1
+                    n_ones = 0
+                    state = '0'
+                else:
+                    n_ones += 1
+            seq_len = 2 * min(n_zeroes, n_ones)
+            best = max(best, seq_len)
+        return best