[LeetCode]#1614. Maximum Nesting Depth of the Parentheses

Environment: Python 3.7

Key technique: max

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)+((8)/4))+1"
Output: 3
Explanation: Digit 8 is inside of 3 nested parentheses in the string.

Analysis:

1. Search input. If the input is ‘(‘, tmp+=1. If the input is is ‘)’, tmp-=1.
2. Find the maximum as an answer.

Solution:

class Solution:
    def maxDepth(self, s):
        ans=0
        tmp=0
        for i in s:
            if (i=='('):
                tmp+=1
                ans=max(ans,tmp)
            elif(i==')'):
                tmp-=1
                ans=max(ans,tmp)
        return ans

Submissions:

Reference:

https://blog.csdn.net/w5688414/article/details/109369137