32 Decode string

06/tasks/task_32_decode_string.py

@@ -5,4 +5,25 @@ def decode_string(s: str) -> str:
     Dekóduje zakódovaný řetězec ve formátu k[encoded_string],
     např. "3[a]2[bc]" → "aaabcbc".
     """
-
+    while '[' in s:
+        pos_left_bracket = s.index('[')
+        pos_right_bracket = s.index(']')
+        # check for nested brackets
+        if '[' in s[pos_left_bracket + 1:]:
+            pos_left_bracket2 = s.index('[', pos_left_bracket + 1)
+        else:
+            pos_left_bracket2 = len(s) + 1
+        # no nested brackets
+        if pos_right_bracket < pos_left_bracket2:
+            pos_num = pos_left_bracket - 1
+            num = ''
+            while s[pos_num].isdigit():
+                num = s[pos_num] + num
+                pos_num += -1
+            s = s[:pos_left_bracket - len(num)] + int(
+                num) * s[pos_left_bracket + 1:pos_right_bracket] + s[pos_right_bracket + 1:]
+        # nested brackets
+        else:
+            s = s[:pos_left_bracket + 1] + \
+                decode_string(s[pos_left_bracket + 1:])
+    return s