LeetCode 20. Valid Parentheses

Description

Given a string containing just the characters

'('

,

')'

,

'{'

,

'}'

,

'['

and

']'

, determine if the input string is valid.

The brackets must close in the correct order,

"()"

and

"()[]{}"

are all valid but

"(]"

and

"([)]"

are not.

Analysis

典型的栈结构应用。

Code

class Solution {
public:
bool isValid(string s) {
stack<char> t;
for (char c : s){
if (c == '(' || c == '{' || c == '[')
t.push(c);
else
switch (c){
case ')':
if (!t.empty() && t.top() == '(')
t.pop();
else return false;
break;
case '}':
if (!t.empty() && t.top() == '{')
t.pop();
else return false;
break;
case ']':
if (!t.empty() && t.top() == '[')
t.pop();
else return false;
break;
default:
return false;
}
}
if (t.empty())
return true;
else return false;
}
};

Appendix

Link: https://leetcode.com/problems/valid-parentheses/

Run Time: 3ms