How should I practice Minimum Insertions to Balance Parentheses?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Google phone screen problems in FastPrep.

Is Minimum Insertions to Balance Parentheses associated with Google?

FastPrep tags this as a Google phone screen coding practice problem when the problem catalog has that company and stage context.

Minimum Insertions to Balance Parentheses

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Problem statement

Given a string s containing only '(' and ')', return the minimum number of parentheses that must be inserted at any positions to make the string valid.

A valid parenthesis string has every opening parenthesis matched with a later closing parenthesis, and every closing parenthesis matched with an earlier opening parenthesis.

Function

minInsertionsToBalance(s: String) → int

Examples

Example 1

s = "())"return = 1

Insert one opening parenthesis before the final closing parenthesis.

Example 2

s = "((("return = 3

Each unmatched opening parenthesis needs a closing parenthesis.

Example 3

s = "()"return = 0

The string is already valid.

Constraints

0 <= s.length <= 100000.
s contains only '(' and ')'.