leetcode 20. Valid Parentheses

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.

解：这是一道简单题，理解算数式子的实现就是利用栈

class Solution {
public:
bool isValid(string s) {
stack<char> tmp;
for(int i = 0; i < s.size(); ++i){
switch(s[i]){
case '(':
case '[':
case '{': tmp.push(s[i]);break;
case ')': if(tmp.empty() || tmp.top() != '(') return false;else tmp.pop();break;
case ']': if(tmp.empty() || tmp.top() != '[') return false;else tmp.pop();break;
case '}': if(tmp.empty() || tmp.top() != '{') return false;else tmp.pop();break;
default: ;
}
}
return tmp.empty();
}
};