adding algo sql

Author: ivanpenaloza

src/my_project/interviews/amazon_high_frequency_23/round_2/design_sql.py

@@ -0,0 +1,94 @@
+from typing import List, Union, Collection, Mapping, Optional, Dict
+
+class Table:
+    def __init__(self, name: str, columns:int, rows: Dict, row_count: int = 0):
+        self.name = name 
+        self.columns = columns
+        self.rows = rows 
+        self.row_count = row_count
+
+class SQL:
+
+    def __init__(self, names: List[str], columns: List[int]):
+        """
+        two string arrays, names and columns, both of size n.
+
+        The ith table is represented by the name names[i] and contains columns[i] number of columns
+        """
+
+        self.names = names
+        self.columns = columns
+        self.data = {}        
+
+        for i in range(0, len(self.names)):
+            self.data[self.names[i]] = Table(
+                self.names[i],
+                self.columns[i],
+                {}
+            )
+
+        return 
+    
+    def ins(self, name: str, row: List[str]) -> bool:
+        """
+        Inserts row into the table name and returns true.
+        If row.length does not match the expected number of columns, or name is not a valid table,
+        returns false without any insertion.
+        """
+        table: Table = self.data.get(name, None)
+        if table is None:
+            return False 
+        if len(row) != table.columns:
+            return False 
+        table.row_count += 1 
+        table.rows[table.row_count] = row
+
+        return True 
+    
+    def rmv(self, name: str, rowId: int) -> None:
+        """
+        Removes the row rowId from the table name.
+        If name is not a valid table or there is no row with id rowId, no removal is performed.
+        """
+        table = self.data.get(name, None)
+        if table is None: 
+            return 
+
+        if rowId in table.rows:
+            del table.rows[rowId]    
+        return 
+    
+    def sel(self, name: str, rowId: int, columnId: int) -> str:
+        """
+        Returns the value of the cell at the specified rowId and columnId in the table name.
+        If name is not a valid table, or the cell (rowId, columnId) is invalid, returns "<null>".
+        """
+        null = "<null>"
+        table = self.data.get(name, None)
+        if table is None:
+            return null 
+
+        if rowId not in table.rows:
+            return null
+
+        try: 
+            return table.rows[rowId][columnId-1]
+        except Exception:
+            return null 
+        
+    def exp(self, name: str) -> List[str]:
+        """
+        Returns the rows present in the table name.
+        If name is not a valid table, returns an empty array.
+        Each row is represented as a string, with each cell value (including the row's id) separated by a ",".
+        """
+        table = self.data.get(name, None)
+        if table is None:
+            return []     
+
+        result = []   
+
+        for row_id, row in table.rows.items():
+            row_str = ",".join(row)
+            result.append(f"{row_id},{row_str}")
+        return result