Variable Expression Truth Evaluation

Medium

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 1

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 2

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 3

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.

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

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Variable Expression Truth Evaluation

Medium

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 1

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 2

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 3

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.

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