leetcode -- Valid Parentheses

不要因为走的太远而忘记我们为什么出发

[问题描述]

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.

[解题思路]

经典括号匹配问题，使用栈模拟即可

bool Solution::isValid(std::string s)
{
std::stack<char> tmp;
for (int i = 0; i < s.length(); i ++){
if (s[i] == '(' || s[i] == '[' || s[i] == '{')
tmp.push(s[i]);
else if (s[i] == ')'){
if (tmp.size() > 0 && tmp.top() == '(')
tmp.pop();
else
return false;
}
else if (s[i] == ']'){
if (tmp.size() > 0 && tmp.top() == '[')
tmp.pop();
else
return false;
}
else if (s[i] == '}'){
if (tmp.size() > 0 && tmp.top() == '{')
tmp.pop();
else
return false;
}
}
return tmp.size() == 0;
}