LeetCode Challenge #20. Valid Parentheses

Day 53 of 100-Days LeetCode Challenge

LeetCode Challenge #20. Valid Parentheses

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

An input string is valid if:

Open brackets must be closed by the same type of brackets.
Open brackets must be closed in the correct order.
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 '()[]{}'.

Video Solution

Java Solution

				
					class Solution {
    public boolean isValid(String s) {
       Stack<Character> st = new Stack<>();

       for(int i=0;i<s.length();i++){
           char ch = s.charAt(i);

           if(ch=='(' || ch=='{' || ch=='['){
               st.push(ch);
           }else if ( st.size()>0 && ch==']' && st.peek()=='['){
               st.pop();
           }else if (st.size()>0 && ch==')' && st.peek()=='('){
                st.pop();
           }else if (st.size()>0 && ch=='}' && st.peek()=='{'){
                st.pop();
           }else{
               return false ;
           }
       }

       if(st.size()==0){
           return true ;
       }else{
           return false ;
       } 
    }
}

Day 53 of 100-Days LeetCode Challenge

LeetCode Challenge #20. Valid Parentheses

Video Solution

Java Solution

Happy Coding with edSlash

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