【leetcode】20. Valid Parentheses
阿新 • • 發佈:2017-07-21
lines fadein cti return nes string data- 復雜度 ack
@requires_authorization
@author johnsondu
@create_time 2015.7.13 11:03
@url [valid parentheses](https://leetcode.com/problems/valid-parentheses/)
/*****************
* 類別: 棧模擬推斷
* 時間復雜度: O(n)
* 空間復雜度: O(n)
****************/
class Solution {
public:
bool isValid(string s) {
stack<char > st;
int len = s.size();
for(int i = 0; i < len; i ++){
if(s[i] == ‘]‘ || s[i] == ‘}‘ || s[i] == ‘)‘){
if(st.empty()){
return false;
}
}
else{
st.push(s[i]);
continue ;
}
if(s[i] == ‘]‘){
char ch = st.top();
st.pop();
if(ch != ‘[‘) return false;
continue;
}
if(s[i] == ‘)‘){
char ch = st.top();
st.pop();
if (ch != ‘(‘) return false;
continue;
}
if(s[i] == ‘}‘){
char ch = st.top();
st.pop();
if(ch != ‘{‘) return false;
continue;
}
}
if(st.empty()) return true;
else return false;
}
};
【leetcode】20. Valid Parentheses