Valid Parentheses Leetcode Solution

by

In this post, we are going to solve the Valid Parentheses Leetcode Solution problem of Leetcode. This Leetcode problem is done in many programming languages like C++, Java, and Python.

Valid Parentheses Leetcode Solution
Valid Parentheses Leetcode Solution

Problem

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

An input string is valid if:

  1. Open brackets must be closed by the same type of brackets.
  2. Open brackets must be closed in the correct order.
  3. Every close bracket has a corresponding open bracket of the same type.

Example 1:

Input: s = "()"
Output: true

Example 2:

Input: s = "()[]{}"
Output: true

Example 3:

Input: s = "(]"
Output: false

Constraints:

  • 1 <= s.length <= 104
  • s consists of parentheses only '()[]{}'.

Now, let’s see the leetcode solution of Valid Parentheses Leetcode Solution.

Valid Parentheses Leetcode Solution in Python

class Solution:
    def isValid(self, s: str) -> bool:
        valid_brack = [('{', '}'), ('(', ')'), ('[', ']')]
        stack = []
        for c in s:
            if len(stack)>0 and (stack[-1], c) in valid_brack:
                stack.pop()
            else:
                stack.append(c)
        return len(stack)==0

Valid Parentheses Leetcode Solution in CPP

class Solution {
public:
    bool isValid(string s) {
        stack<char> st;
        
        for(char c: s){
            if(c == '(' || c == '{' || c == '['){
                st.push(c);
            }
            else{
                if(st.empty()){
                    return false;
                }
                if(c==')' and st.top()=='('){
                    st.pop();
                }
                else if(c=='}' and st.top()=='{'){
                    st.pop();
                }
                else if(c==']' and st.top()=='['){
                    st.pop();
                }
                else{
                    return false;
                }
            }
        }
        if(st.empty()){
            return true;
        }
        return false;
    }
};

Valid Parentheses Leetcode Solution in Java

class Solution {
    
    public boolean handleClosing(Stack<Character> s, char openBracket){
        if(s.size() == 0){
            return false;
        }else if(s.peek() != openBracket){
            return false;
        }else {
            s.pop();
        }
        return true;
    }
    public boolean isValid(String s) {
        Stack<Character> stack = new Stack<>();
        for(char ch : s.toCharArray()){
            if(ch == '(' || ch == '{' || ch == '['){
                stack.push(ch);
            }else if(ch == ')'){
                boolean val = handleClosing(stack,'(');
                if(val == false) return false;
            }else if(ch == '}'){
                boolean val = handleClosing(stack,'{');
                if(val == false) return false;
            }else if(ch == ']'){
                boolean val = handleClosing(stack,'[');
                if(val == false) return false;
            }
        }
        
        if(stack.size() > 0)return false;
        return true;
    }
}

Note: This problem Valid Parentheses is generated by Leetcode but the solution is provided by Chase2learn This tutorial is only for Educational and Learning purposes.

NOTE: Merge Two Sorted Lists

Sharing Is Caring

Leave a Comment