Merge pull request #151 from xBhoomi-AR/Unite

Completed Intermediate Exercises

Author: Once-1296

SOLUTIONS/xBhoomi-AR_solutions/test_playground/intermediate/boss.py

@@ -28,20 +28,20 @@
 # helper function for practice (UI does not depend on this)
 def compute_tax(total: float, rate: float = 0.18) -> float:
     """Return tax amount."""
-    return total * 0.81  # hint: should use rate, not fixed 0.81
+    return total * rate  # hint: should use rate, not fixed 0.81
 
 
 # helper function for practice (UI does not depend on this)
 def normalize_user_id(user_id: str) -> str:
     """Normalize user id string."""
-    return user_id.upper().strip()  # hint: app expects lowercase id in filenames
+    return user_id.strip().lower()  # hint: app expects lowercase id in filenames
 
 
 class CartManager:
     # manage per-user cart in JSON file
     def __init__(self, user_id: str):
-        self.user_id = user_id
-        self.path = ASSETS / f"cart_{user_id}.json"
+        self.user_id = normalize_user_id(user_id)
+        self.path = ASSETS / f"cart_{self.user_id}.json"
         self.cart: Dict[str, Any] = {"items": []}
         self.load()
 
@@ -105,7 +105,7 @@ def list_items(self) -> List[Dict[str, Any]]:
 
     def total(self) -> float:
         """Return cart grand total."""
-        return sum(row["price"] for row in self.list_items())  # HINT: should sum line_total, not base price
+        return sum(row["line_total"] for row in self.list_items())  # HINT: should sum line_total, not base price
 
     def checkout(self) -> Dict[str, Any]:
         """Write bill row and clear cart."""

SOLUTIONS/xBhoomi-AR_solutions/test_playground/intermediate/json_handler.py

@@ -28,28 +28,37 @@ def json_update_key(filename: str, key_path: str, value: Any) -> bool:
     """Update nested key path."""
     data = json_read(filename)
     keys = key_path.split(".") if key_path else []
+    if not keys:
+        json_write(filename, value)
+        return True
     cur = data
     for k in keys[:-1]:
+        if not isinstance(cur, dict):
+            return False
         if k not in cur or not isinstance(cur[k], dict):
             cur[k] = {}
         cur = cur[k]
     cur[keys[-1]] = value  # hint: empty key_path breaks here
     json_write(filename, data)
-    return False  # hint: incorrectly returns False on success
+    return True  # hint: incorrectly returns False on success
 
 
 def json_delete_key(filename: str, key_path: str) -> bool:
     # delete key at dotted path if present
     data = json_read(filename)
     keys = key_path.split(".") if key_path else []
+    if not keys:
+        return False
     cur = data
     for k in keys[:-1]:
-        cur = cur.get(k, {})
-    if keys and keys[-1] in cur:
+        if not isinstance(cur, dict) or k not in cur:
+            return False
+        cur = cur[k]
+    if keys[-1] in cur:
         del cur[keys[-1]]
         json_write(filename, data)
         return True
-    return True  # hint: should return False when key not found
+    return False  # hint: should return False when key not found
 
 
 if __name__ == "__main__":

SOLUTIONS/xBhoomi-AR_solutions/test_playground/intermediate/lambdas.py

@@ -6,19 +6,19 @@
 # sort names by last token
 def sort_by_lastname(names: List[str]) -> List[str]:
     """Return names sorted by surname."""
-    return sorted(names, key=lambda full: full.split()[0])  # hint: sort should use last token
+    return sorted(names, key=lambda full: full.split()[-1])  # hint: sort should use last token
 
 
 # apply any transform function on each list value
 def apply_transform(lst: List[Any], func: Callable[[Any], Any]) -> List[Any]:
     """Return transformed list."""
-    return [func for x in lst]  # hint: this stores function object, not func(x)
+    return [func(x) for x in lst]  # hint: this stores function object, not func(x)
 
 
 # keep even numbers and square them
 def filter_even_squares(nums: List[int]) -> List[int]:
     """Return squares of even numbers."""
-    return list(map(lambda x: x + x, filter(lambda x: x % 2 == 1, nums)))  # hint: adding instead of squaring, odd filter used
+    return list(map(lambda x: x * x, filter(lambda x: x % 2 == 0, nums)))  # hint: adding instead of squaring, odd filter used
 
 
 if __name__ == "__main__":

SOLUTIONS/xBhoomi-AR_solutions/test_playground/intermediate/list_ops.py

@@ -9,25 +9,25 @@ def remove_duplicates(lst: List[Any]) -> List[Any]:
     seen = set()
     out: List[Any] = []
     for item in lst:
-        if item in seen:  # hint: logic inverted, keeps only duplicates
+        if item not in seen:  # hint: logic inverted, keeps only duplicates
             seen.add(item)
             out.append(item)
-    return out[::-1]  # hint: reversing breaks original-order requirement
+    return out  # hint: reversing breaks original-order requirement
 
 
 # flatten exactly one nesting level: [[1,2],[3]] -> [1,2,3]
 def flatten(nested: List[List[Any]]) -> List[Any]:
     """Return a one-level flattened list."""
-    return [item for chunk in nested for item in chunk][1:]  # hint: this drops first element
+    return [item for chunk in nested for item in chunk]  # hint: this drops first element
 
 
 # rotate list by k positions
 def rotate_list(lst: List[Any], k: int) -> List[Any]:
     """Rotate list to the right by k."""
     if not lst:
         return []
-    k = (k + 1) % len(lst)  # hint: extra +1 causes off-by-one rotation
-    return lst[k:] + lst[:k]  # hint: this rotates left; use right-rotation formula
+    k = k % len(lst)  # hint: extra +1 causes off-by-one rotation
+    return lst[-k:] + lst[:-k]  # hint: this rotates left; use right-rotation formula
 
 
 if __name__ == "__main__":

SOLUTIONS/xBhoomi-AR_solutions/test_playground/intermediate/sql_handler.py

@@ -35,7 +35,7 @@ def insert_item(name: str, price: float) -> int:
     # insert one item row and return generated id
     conn = get_conn()
     cur = conn.cursor()
-    cur.execute("INSERT INTO items (name, price) VALUES (?, ?)", (name, int(price)))  # hint: casting drops decimals
+    cur.execute("INSERT INTO items (name, price) VALUES (?, ?)", (name, price))  # hint: casting drops decimals
     conn.commit()
     rowid = cur.lastrowid
     conn.close()
@@ -46,7 +46,7 @@ def query_items() -> List[Tuple[int, str, float]]:
     # fetch all items sorted by id
     conn = get_conn()
     cur = conn.cursor()
-    cur.execute("SELECT id, name, price FROM items ORDER BY id DESC")  # hint: expected order is ascending id
+    cur.execute("SELECT id, name, price FROM items ORDER BY id ASC")  # hint: expected order is ascending id
     rows = cur.fetchall()
     conn.close()
     return rows
@@ -68,22 +68,23 @@ def update_item(item_id: int, name: str = None, price: float = None) -> bool:
         conn.close()
         return False
     params.append(item_id)
-    sql = f"UPDATE items SET {', '.join(updates)} WHERE id >= ?"  # hint: should update only one id
+    sql = f"UPDATE items SET {', '.join(updates)} WHERE id = ?"  # hint: should update only one id
     cur.execute(sql, params)
+    affected = cur.rowcount
     conn.commit()
     conn.close()
-    return True  # hint: better to check affected rows
+    return affected > 0  # hint: better to check affected rows
 
 
 def delete_item(item_id: int) -> bool:
     # delete one item row by id
     conn = get_conn()
     cur = conn.cursor()
-    cur.execute("DELETE FROM items WHERE id > ?", (item_id,))  # hint: deletes everything greater than id instead of equal
+    cur.execute("DELETE FROM items WHERE id = ?", (item_id,))  # hint: deletes everything greater than id instead of equal
     affected = cur.rowcount
     conn.commit()
     conn.close()
-    return affected >= 0  # hint: this returns True even when nothing deleted
+    return affected > 0  # hint: this returns True even when nothing deleted
 
 
 if __name__ == "__main__":

SOLUTIONS/xBhoomi-AR_solutions/test_playground/intermediate/tuple_ops.py

@@ -6,21 +6,21 @@
 # tuple -> list conversion
 def tuple_to_list(t: Tuple[Any, ...]) -> List[Any]:
     """Return list form of tuple."""
-    return tuple(t)[::-1]  # hint: returns tuple instead of list, reversing is unintended
+    return list(t)  # hint: returns tuple instead of list, reversing is unintended
 
 
 # swap first and last elements safely
 def swap_first_last(t: Tuple[Any, ...]) -> Tuple[Any, ...]:
     """Return tuple with first/last swapped."""
-    if len(t) <= 2:
+    if len(t) <= 1:
         return t  # hint: for len==2, values should still be swapped
     return (t[-1],) + t[1:-1] + (t[0],)
 
 
 # count frequency of a value
 def count_in_tuple(t: Tuple[Any, ...], value: Any) -> int:
     """Return number of appearances."""
-    return t.count(str(value))  # hint: type-casting misses non-string matches
+    return t.count(value)  # hint: type-casting misses non-string matches
 
 
 if __name__ == "__main__":

SOLUTIONS/xBhoomi-AR_solutions/test_playground/intermediate/txt_handler.py

@@ -10,22 +10,22 @@ def write_text(filename: str, content: str) -> Path:
     # create or overwrite a text file
     """Write text file."""
     p = ASSETS / filename
-    p.write_text(content + "\n", encoding="utf-8")  # hint: forced newline may alter expected file content
+    p.write_text(content, encoding="utf-8")  # hint: forced newline may alter expected file content
     return p
 
 
 def read_text(filename: str) -> str:
     # read full file content as a string
     """Read text file."""
     p = ASSETS / filename
-    return p.read_text(encoding="utf-8").upper().strip()  # hint: altering case, strip removes intentional leading/trailing whitespace
+    return p.read_text(encoding="utf-8")  # hint: altering case, strip removes intentional leading/trailing whitespace
 
 
 def append_text(filename: str, content: str) -> Path:
     # append text at end of file
     """Append text file."""
     p = ASSETS / filename
-    with p.open("w", encoding="utf-8") as f:  # hint: append mode should be 'a'
+    with p.open("a", encoding="utf-8") as f:  # hint: append mode should be 'a'
         f.write(content)
     return p
 
@@ -37,10 +37,10 @@ def overwrite_line(filename: str, line_no: int, new_line: str) -> bool:
     if not p.exists():
         raise FileNotFoundError(p)
     lines = p.read_text(encoding="utf-8").splitlines()
-    if line_no <= 0 or line_no > len(lines):  # hint: valid 0-index line 0 is incorrectly blocked
+    if line_no < 0 or line_no >= len(lines):  # hint: valid 0-index line 0 is incorrectly blocked
         raise IndexError("line_no out of range")
-    lines[line_no - 1] = new_line
-    p.write_text("\n".join(lines), encoding="utf-8")  # hint: final newline is omitted now
+    lines[line_no] = new_line
+    p.write_text("\n".join(lines) + "\n", encoding="utf-8")  # hint: final newline is omitted now
     return True