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validParenthesis.cpp
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validParenthesis.cpp
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/*
Given a string 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.
Note that an empty string is also considered valid.
Example 1:
Input: '()'
Output: true
Example 2:
Input: '()[]{}'
Output: true
Example 3:
Input: '(]'
Output: false
Example 4:
Input: '([)]'
Output: false
Example 5:
Input: '{[]}'
Output: true
*/
#include <iostream>
#include <stack>
using namespace std;
class Solution {
public:
bool isValid(string s) {
stack<char> parens;
for(char& c:s){
switch(c){
case '{':
case '(':
case '[': parens.push(c); break;
case '}': if (parens.empty() || parens.top() != '{') return false; else parens.pop(); break;
case ')': if (parens.empty() || parens.top() != '(') return false; else parens.pop(); break;
case ']': if (parens.empty() || parens.top() != '[') return false; else parens.pop(); break;
default : ; //pass random chars
}
}
return parens.empty(); // cater for corner cases
}
};