21
04/2015
[LeetCode] Valid Parentheses
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.
解题思路：
比较简单，用栈即可。遇到左括号，入栈，遇到右括号，查看栈顶元素是否匹配。注意可能空栈的情况。
class Solution {
public:
bool isValid(string s) {
int len=s.length();
stack<char> st;
for(int i=0; i<len; i++){
switch(s[i]){
case '(':
case '{':
case '[':
st.push(s[i]);
break;
case '}':
if(st.empty()||st.top()!='{'){
return false;
}
st.pop();
break;
case ']':
if(st.empty()||st.top()!='['){
return false;
}
st.pop();
break;
case ')':
if(st.empty()||st.top()!='('){
return false;
}
st.pop();
break;
default:
return false;
}
}
return st.empty();
}
};转载请注明：康瑞部落 » [LeetCode] Valid Parentheses
0 条评论