Variable Expression Truth Evaluation

MEDIUM20 pts

A rules engine stores named integer values and a set of comparison rules.

Table: variables

name: unique variable identifier
value: integer value bound to that variable

Table: expressions

left_operand: variable name on the left side
operator: one of '<', '>', '='
right_operand: variable name on the right side
(left_operand, operator, right_operand) is unique

Guarantees:

Every operand name in expressions exists in variables.name.

Task: Evaluate every rule in expressions by reading operand values from variables. For each expression row, output whether the comparison is true or false.

Output requirements:

Return exactly these columns: left_operand, operator, right_operand, value
value must be the lowercase string 'true' or 'false'
The output can be returned in any order.

Supported submission environments:

SQL (SQLite 3.27.2)
Pandas (Python)

Example

Input

variables:
| name | value |
|------|-------|
| alpha| 42    |
| beta | 19    |
| gamma| 42    |

expressions:
| left_operand | operator | right_operand |
|--------------|----------|---------------|
| alpha        | >        | beta          |
| beta         | <        | alpha         |
| alpha        | =        | gamma         |
| beta         | =        | gamma         |

Output

[
  {"left_operand":"alpha","operator":">","right_operand":"beta","value":"true"},
  {"left_operand":"beta","operator":"<","right_operand":"alpha","value":"true"},
  {"left_operand":"alpha","operator":"=","right_operand":"gamma","value":"true"},
  {"left_operand":"beta","operator":"=","right_operand":"gamma","value":"false"}
]

Explanation

Each expression compares two looked-up integers from variables and emits a textual boolean.

Example

Input

variables:
| name | value |
|------|-------|
| x1   | -5    |
| x2   | -5    |
| x3   | 0     |

expressions:
| left_operand | operator | right_operand |
|--------------|----------|---------------|
| x1           | =        | x2            |
| x1           | <        | x3            |
| x3           | >        | x2            |

Output

[
  {"left_operand":"x1","operator":"=","right_operand":"x2","value":"true"},
  {"left_operand":"x1","operator":"<","right_operand":"x3","value":"true"},
  {"left_operand":"x3","operator":">","right_operand":"x2","value":"true"}
]

Explanation

Negative values and zero follow normal integer comparison semantics.

Example

Input

variables:
| name | value |
|------|-------|
| a    | 100   |
| b    | 100   |

expressions:
| left_operand | operator | right_operand |
|--------------|----------|---------------|
| a            | <        | b             |
| a            | >        | b             |
| a            | =        | b             |

Output

[
  {"left_operand":"a","operator":"<","right_operand":"b","value":"false"},
  {"left_operand":"a","operator":">","right_operand":"b","value":"false"},
  {"left_operand":"a","operator":"=","right_operand":"b","value":"true"}
]

Explanation

When both operand values are equal, only '=' evaluates to true.

Accepted0/0·0% Acceptance

Constraints

0 <= number of rows in variables <= 100000
0 <= number of rows in expressions <= 200000
name is a non-empty string and unique in variables
value is a signed 32-bit integer
operator is exactly one of: '<', '>', '='
(left_operand, operator, right_operand) is unique in expressions
Every operand in expressions appears in variables.name
Return exactly four columns: left_operand, operator, right_operand, value
value must be lowercase textual boolean: 'true' or 'false'
For SQL submissions, use SQLite 3.27.2 semantics
For Pandas submissions, return a DataFrame with required columns

Code

Visualizer

Solutions

14px

Test Cases3

Results

Submissions

variables =

[{"name":"alpha","value":42},{"name":"beta","value":19},{"name":"gamma","value":42}]

expressions =

[{"left_operand":"alpha","operator":">","right_operand":"beta"},{"left_operand":"beta","operator":"<","right_operand":"alpha"},{"left_operand":"alpha","operator":"=","right_operand":"gamma"},{"left_operand":"beta","operator":"=","right_operand":"gamma"},{"left_operand":"beta","operator":">","right_operand":"alpha"}]

Variable Expression Truth Evaluation

Hints

Variable Expression Truth Evaluation

Hints