题目
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.
分析
可以用栈来实现。碰到左边的括号就入栈，碰到右边的就出栈，并判断是否匹配。
实现
class Solution {
public:
bool isValid(string s) {
stack<int> Stack;
map<char, char> Map={{'(',')'}, {'{','}'}, {'[',']'}};
for(auto ch: s){
if(ch=='('||ch=='{'||ch=='[')
Stack.push(ch);
else{
if((!Stack.empty())&&Map[Stack.top()]==ch)
Stack.pop();
else
return false;
}
}
if(Stack.empty())
return true;
else
return false;
}
};
思考
一开始忘记了碰到右括号时要先判断栈是否非空，还是要细心呀。
