Tutorialspoint
Problem
Solution
Submissions
Back

Valid Parentheses

Certification: Basic Level Accuracy: 49.23% Submissions: 65 Points: 5

Write a Java program to implement the isValid(String s) function, which determines if an input string containing just the characters '(', ')', '{', '}', '[' and ']' is valid.

Example 1
    

  • Input: s = "()"
    • 

  • Output: true
    • 

  • Explanation:

      

    • Push '(' → Stack = ['(']
      • 

    • Encounter ')' → Matches top, pop '('
      • 

    • Stack is empty → valid
      • 

    

    •
Example 2
    

  • Input: s = "([)]"
    • 

  • Output: false
    • 

  • Explanation:

      

    • Push '(' → Push '['
      • 

    • ')' does not match top '[' → invalid
      • 

    

    •
Constraints
    

  • 1 ≤ s.length ≤ 10^4
    • 

  • s consists of parentheses only '()[]{}'
    • 

  • Time Complexity: O(n)
    • 

  • Space Complexity: O(n)
    •
StringsStackCapgeminiLTIMindtree
Editorial

Login to view the detailed solution and explanation for this problem.

My Submissions
All Solutions
Refresh
Lang Status Date Code
You do not have any submissions for this problem.
Refresh
User Lang Status Date Code
No submissions found.

Please Login to continue
Solve Problems

 
 
 
Output Window
Clear All Apply Filters

Trending

Others

SIGN IN

Don't have an account? Register

Hint
Solution

Solution Hints

    
  
  • Use a stack to keep track of opening brackets
    • 
  
  • When you encounter an opening bracket, push it onto the stack
    • 
  
  • When you encounter a closing bracket, check if the stack is empty or if the top element is the corresponding opening bracket
    • 
  
  • If the stack is not empty at the end, the string is invalid
    •

Steps to solve by this approach:

 Step 1: Create a stack to store opening brackets.
 Step 2: Iterate through each character in the string.
 Step 3: If the character is an opening bracket ('(', '[', '{'), push it onto the stack.
 Step 4: If the character is a closing bracket (')', ']', '}'), check if the stack is empty.
 Step 5: If stack is not empty, pop the top element and verify it matches the current closing bracket.
 Step 6: If no match or stack is empty, return false.
 Step 7: After processing all characters, return true if stack is empty, false otherwise.

Submitted Code :