1614. Maximum Nesting Depth of the Parentheses

LeetCode 1614. Maximum Nesting Depth of the Parentheses

Description

A string is a valid parentheses string (denoted VPS ) if it meets one of the following:

• It is an empty string "", or a single character not equal to "(" or ")",

• It can be written as AB (A concatenated with B), where A and B are VPS 's, or

• It can be written as (A), where A is a VPS.

We can similarly define the nesting depth depth(S) of any VPS S as follows:

• depth("") = 0

• depth(C) = 0, where C is a string with a single character not equal to "(" or ")".

• depth(A + B) = max(depth(A), depth(B)), where A and B are VPS 's.

• depth("(" + A + ")") = 1 + depth(A), where A is a VPS.

For example, "", "()()", and "()(()())" are VPS 's (with nesting depths 0, 1, and 2), and ")(" and "(()" are not VPS 's.

Given a VPS represented as string s, return the nesting depth of s.

Example 1:

Input: s = "(1)+((2))+(((3)))"
Output: 3

Constraints:

• 1 <= s.length <= 100

• s consists of digits 0-9 and characters '+', '-', '*', '/', '(', and ')'.

• It is guaranteed that parentheses expression s is a VPS.

Tags

String

Solution

Define a variable to track the depth. If we come across '(' then depth add 1; if ')' then depth minus 1. We also need to update the max value of the depth, and return it as the result in the end.

Complexity

• Time complexity: $O(n)$

• Space complexity: $O(n)$

Code

func maxDepth(s string) int {
	var count, ans int
	for _, c := range s {
		if c == '(' {
			count++
			if count > ans {
				ans = count
			}
		} else if c == ')' {
			count--
		}
	}
	return ans
}