Practice/Google/String Resolution and Variable Update

String Resolution and Variable Update

CodingOptional

Problem

Design a system that manages string variables with dynamic resolution capabilities. Your system needs to handle two core operations:

1. Variable Resolution: Process strings that contain variable references (prefixed with %) and replace them with their actual values. Variables can reference other variables, requiring recursive resolution.
2. Variable Updates: Modify variable values dynamically, which affects all subsequent resolutions.

For example, if you have variables x = 'hello' and y = '%x world', resolving %y should produce 'hello world' by first resolving %x within the value of y.

Requirements

1. Implement resolveString(s, variables) that takes an input string and a dictionary of variables, returning the fully resolved string
2. Variable references start with % followed by the variable name (single character or word)
3. Handle nested variable references where one variable's value contains references to other variables
4. Implement updateVariable(var, value, variables) to modify variable values
5. Variables without a % prefix in their values are literal strings
6. Handle cases where strings contain no variable references

Constraints

• Variable names consist of alphanumeric characters
• Maximum recursion depth should be reasonable (assume no circular references in test cases)
• 1 ≤ string length ≤ 1000
• 1 ≤ number of variables ≤ 100
• Time complexity should be O(n × m) where n is string length and m is average resolution depth
• Space complexity should be O(n) for the result string

Examples

Example 1:

Variables: \{x: 'tech', y: 'interview'\} Input: "Welcome to %x %y" Output: "Welcome to tech interview" Explanation: Direct substitution of %x and %y with their values

Example 2:

Variables: \{x: 'Python', y: '%x programming', z: 'I love %y'\} Input: "%z" Output: "I love Python programming" Explanation: %z resolves to 'I love %y', which then resolves %y to '%x programming', finally resolving %x to 'Python'

Example 3:

Variables: \{x: 'old'\} After updateVariable('x', 'new', variables) Variables: \{x: 'new', y: '%x data'\} Input: "%y" Output: "new data" Explanation: After updating x, subsequent resolutions use the new value

Example 4:

Variables: \{x: 'test'\} Input: "No variables here" Output: "No variables here" Explanation: Strings without variable references return unchanged