Balanced Brackets Sequel - Amazon Top Interview Questions


Problem Statement :


Given a string s containing round, curly, and square open and closing brackets, return whether the brackets are balanced.

Constraints

n ≤ 100,000 where n is the length of s

Example 1

Input

s = "[(])"

Output

False

Example 2

Input

s = "([])[]({})"

Output

True


Solution :



title-img 




                        Solution in C++ :

bool solve(string s) {
    stack<char> stack;

    for (char c : s) {
        if (c == '(' || c == '{' || c == '[')
            stack.push(c);
        else {
            if (stack.empty())
                return false;
            else if (c == ')' && stack.top() != '(')
                return false;
            else if (c == '}' && stack.top() != '{')
                return false;
            else if (c == ']' && stack.top() != '[')
                return false;
            else
                stack.pop();
        }
    }

    return stack.empty();
}
                    




                        Solution in Python : 
                            
class Solution:
    def solve(self, s):
        # The stack to keep track of opening brackets.
        stack = []

        # Hash map for keeping track of mappings. This keeps the code very clean.
        # Also makes adding more types of parenthesis easier
        mapping = {")": "(", "}": "{", "]": "["}

        for char in s:
            # if char is a closing bracket
            if char in mapping:
                # Pop the top most element else #, the top most element must be an opening bracket
                # of the same type
                top = stack.pop() if stack else "#"

                if mapping[char] != top:
                    return False
            else:
                stack.append(char)

        # if the stack is empty, we have a valid expression
        # the stack wont be empty for cases like (()
        return not stack


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