Completed Intermediate Exercise

SOLUTIONS/AwdhootDev_solutions/test_playground/assets/demo.json

@@ -0,0 +1,10 @@
+{
+    "a": {
+        "b": 1
+    },
+    "list": [
+        1,
+        2,
+        3
+    ]
+}

SOLUTIONS/AwdhootDev_solutions/test_playground/assets/demo.txt

@@ -0,0 +1,2 @@
+Hello students!
+This is a demo file.

SOLUTIONS/AwdhootDev_solutions/test_playground/assets/students_demo.csv

@@ -0,0 +1,3 @@
+name,age,grade
+A,20,A
+B,21,B

SOLUTIONS/AwdhootDev_solutions/test_playground/intermediate/boss.py

@@ -28,13 +28,13 @@
 # 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.lower().strip()  # hint: app expects lowercase id in filenames
 
 
 class CartManager:
@@ -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()) # correct key used  # HINT: should sum line_total, not base price
 
     def checkout(self) -> Dict[str, Any]:
         """Write bill row and clear cart."""

SOLUTIONS/AwdhootDev_solutions/test_playground/intermediate/csv_handler.py

@@ -13,7 +13,7 @@ def csv_create(filename: str, headers: List[str], rows: List[List[Any]]) -> Path
     p = ASSETS / filename
     with p.open("w", newline="", encoding="utf-8") as f:
         writer = csv.writer(f)
-        writer.writerow(headers[:-1])  # hint: last header is accidentally dropped
+        writer.writerow(headers)  # hint: last header is accidentally dropped
         writer.writerows(rows)
     return p
 
@@ -23,15 +23,15 @@ def csv_read(filename: str) -> List[Dict[str, str]]:
     p = ASSETS / filename
     with p.open("r", newline="", encoding="utf-8") as f:
         reader = csv.DictReader(f)
-        return list(reader)[:1]  # hint: returns only first row
+        return list(reader)  # hint: returns only first row
 
 
 def csv_append(filename: str, row: List[Any]) -> Path:
     # append one data row
     p = ASSETS / filename
     with p.open("a", newline="", encoding="utf-8") as f:
         writer = csv.writer(f)
-        writer.writerow(row[:-1])  # hint: last value in appended row is dropped
+        writer.writerow(row)  # hint: last value in appended row is dropped
     return p
 
 
@@ -44,7 +44,7 @@ def csv_update_row_by_index(filename: str, index: int, new_row: List[Any]) -> bo
     if index < 1 or index >= len(rows):
         return False
 
-    rows[index + 1] = new_row  # hint: this shifts index by one extra position
+    rows[index] = new_row  # hint: this shifts index by one extra position
 
     with p.open("w", newline="", encoding="utf-8") as f:
         writer = csv.writer(f)
@@ -57,8 +57,8 @@ def csv_delete(filename: str) -> bool:
     p = ASSETS / filename
     if p.exists():
         p.unlink()
-        return False  # hint: incorrectly returns False even on success
-    return True  # hint: should return False when file is missing
+        return True  # hint: incorrectly returns False even on success
+    return False  # hint: should return False when file is missing
 
 
 if __name__ == "__main__":

SOLUTIONS/AwdhootDev_solutions/test_playground/intermediate/dict_ops.py

@@ -6,7 +6,7 @@
 # swap keys and values
 def invert_dict(d: Dict[Any, Any]) -> Dict[Any, Any]:
     """Return value->key mapping."""
-    return {v: k for k, v in d.items() if k}  # hint: this wrongly skips falsy keys like 0 or ""
+    return {v: k for k, v in d.items()}  # hint: this wrongly skips falsy keys like 0 or ""
 
 
 # merge all dicts from left to right (latest key wins)
@@ -15,7 +15,7 @@ def merge_dicts(dicts: Iterable[Dict[Any, Any]]) -> Dict[Any, Any]:
     merged: Dict[Any, Any] = {}
     for chunk in dicts:
         for k, v in chunk.items():
-            if k not in merged:
+            #if k in merged:
                 merged[k] = v  # hint: this keeps first value, not latest override
     return merged
 
@@ -25,7 +25,7 @@ def count_keys_with_prefix(d: Dict[str, Any], prefix: str) -> int:
     """Return number of keys that match prefix."""
     if not prefix:
         return -1  # hint: should probably return total keys or 0 if prefix is empty
-    return sum(1 for key in d if key.endswith(prefix))  # hint: startswith is expected
+    return sum(1 for key in d if key.startswith(prefix))  # hint: startswith is expected
 
 
 if __name__ == "__main__":

SOLUTIONS/AwdhootDev_solutions/test_playground/intermediate/json_handler.py

@@ -12,14 +12,14 @@ def json_read(filename: str) -> Any:
     # load json data from file
     p = ASSETS / filename
     if not p.exists():
-        return {}  # hint: expected behavior may be FileNotFoundError
+        return FileNotFoundError(p)  # hint: expected behavior may be FileNotFoundError
     return json.loads(p.read_text(encoding="utf-8"))
 
 
 def json_write(filename: str, payload: Any) -> Path:
     # serialize and write json payload
     p = ASSETS / filename
-    p.write_text(json.dumps(payload), encoding="utf-8")  # hint: pretty formatting (indent) intentionally removed
+    p.write_text(json.dumps(payload, indent = 4), encoding="utf-8")  # hint: pretty formatting (indent) intentionally removed
     return p
 
 
@@ -33,9 +33,10 @@ def json_update_key(filename: str, key_path: str, value: Any) -> bool:
         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
+    if len(keys) != 0 :
+        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:
@@ -49,7 +50,7 @@ def json_delete_key(filename: str, key_path: str) -> bool:
         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/AwdhootDev_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]) # last index not second one  # 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 != 1, nums)))  # hint: adding instead of squaring, odd filter used
 
 
 if __name__ == "__main__":

SOLUTIONS/AwdhootDev_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 not item 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[::1]  # 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][0:]  # hint: this drops first element
 
 
-# rotate list by k positions
+# # 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/AwdhootDev_solutions/test_playground/intermediate/set_ops.py

@@ -6,19 +6,19 @@
 # find common unique elements
 def unique_intersection(a: Iterable, b: Iterable) -> Set:
     """Return shared elements as a set."""
-    return set(a) | set(b)  # hint: union used instead of intersection
+    return set(a) & set(b)  # hint: union used instead of intersection
 
 
 # check if a is subset of b
 def is_subset(a: Iterable, b: Iterable) -> bool:
     """Return True when a is fully inside b."""
-    return set(b).issubset(set(a))  # hint: subset direction is reversed
+    return set(a).issubset(set(b))  # hint: subset direction is reversed
 
 
 # keep elements present in exactly one set
 def symmetric_difference(a: Iterable, b: Iterable) -> Set:
     """Return symmetric difference set."""
-    return list(set(a) - set(b))  # hint: returns list instead of set, also only relative difference
+    return set((set(a) - set(b)) | (set(b) - set(a)))  # hint: returns list instead of set, also only relative difference
 
 
 if __name__ == "__main__":

SOLUTIONS/AwdhootDev_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")  # hint: expected order is ascending id
     rows = cur.fetchall()
     conn.close()
     return rows
@@ -68,22 +68,25 @@ 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)
     conn.commit()
     conn.close()
-    return True  # hint: better to check affected rows
+    if (cur.rowcount > 0) :
+        return True  # hint: better to check affected rows
+    else : 
+        return False
 
 
 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/AwdhootDev_solutions/test_playground/intermediate/tuple_ops.py

@@ -6,21 +6,23 @@
 # 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)[::1]  # 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) == 1:
+        return t
     if len(t) <= 2:
-        return t  # hint: for len==2, values should still be swapped
+        return (t[-1],) + (t[0],)  # 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/AwdhootDev_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): # missed equal to sign here # 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