[1] fix bst for sorted records

raskatovia/docs/data/task1/spravochnik.py

@@ -76,14 +76,24 @@ def ht_list_all(buckets):
     return sort_records(records)
 
 def bst_insert(root, name, phone):
+    new_node = {"name": name, "phone": phone, "left": None, "right": None}
     if root is None:
-        return {"name": name, "phone": phone, "left": None, "right": None}
-    if name < root["name"]:
-        root["left"] = bst_insert(root["left"], name, phone)
-    elif name > root["name"]:
-        root["right"] = bst_insert(root["right"], name, phone)
-    else:
-        root["phone"] = phone
+        return new_node
+    current = root
+    while True:
+        if name < current["name"]:
+            if current["left"] is None:
+                current["left"] = new_node
+                break
+            current = current["left"]
+        elif name > current["name"]:
+            if current["right"] is None:
+                current["right"] = new_node
+                break
+            current = current["right"]
+        else:
+            current["phone"] = phone
+            break
     return root
 
 def bst_find(root, name):
@@ -97,38 +107,48 @@ def bst_find(root, name):
             current = current["right"]
     return None
 
-def bst_min_node(root):
-    current = root
-    while current["left"] is not None:
-        current = current["left"]
-    return current
-
 def bst_delete(root, name):
-    if root is None:
-        return None
-    if name < root["name"]:
-        root["left"] = bst_delete(root["left"], name)
+    parent = None
+    current = root
+    while current is not None and current["name"] != name:
+        parent = current
+        if name < current["name"]:
+            current = current["left"]
+        else:
+            current = current["right"]
+    if current is None:
         return root
-    if name > root["name"]:
-        root["right"] = bst_delete(root["right"], name)
-        return root
-    if root["left"] is None:
-        return root["right"]
-    if root["right"] is None:
-        return root["left"]
-    replacement = bst_min_node(root["right"])
-    root["name"] = replacement["name"]
-    root["phone"] = replacement["phone"]
-    root["right"] = bst_delete(root["right"], replacement["name"])
+    if current["left"] is not None and current["right"] is not None:
+        replacement_parent = current
+        replacement = current["right"]
+        while replacement["left"] is not None:
+            replacement_parent = replacement
+            replacement = replacement["left"]
+        current["name"] = replacement["name"]
+        current["phone"] = replacement["phone"]
+        parent = replacement_parent
+        current = replacement
+    if current["left"] is not None:
+        child = current["left"]
+    else:
+        child = current["right"]
+    if parent is None:
+        return child
+    if parent["left"] is current:
+        parent["left"] = child
+    else:
+        parent["right"] = child
     return root
 
 def bst_list_all(root):
     records = []
-    def walk(node):
-        if node is None:
-            return
-        walk(node["left"])
-        records.append((node["name"], node["phone"]))
-        walk(node["right"])
-    walk(root)
+    stack = []
+    current = root
+    while current is not None or stack:
+        while current is not None:
+            stack.append(current)
+            current = current["left"]
+        current = stack.pop()
+        records.append((current["name"], current["phone"]))
+        current = current["right"]
     return records