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.
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分析：
遇到‘(‘, ‘{‘, ‘[‘ 就入栈，遇到‘)‘, ‘}‘, ‘]‘ 就和栈顶元素进行对比，相同则继续，不同返回false
其他false情形：
当对比时，栈已经empty了
代码
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class Solution {
public:
bool isValid(string s) {
stack<char> stk;
int len = s.size();
if(0 >= len) return false;
for(int i = 0; i < len; ++i){
if(s[i] == ‘(‘ || s[i] == ‘[‘ || s[i] == ‘{‘){
stk.push(s[i]);
}
else{
if(stk.empty()){
return false;
}
else{
if(match(stk.top(),s[i])){
stk.pop();
}
else{
return false;
}
}
}
}
if(stk.empty())
return true;
else
return false;
}
bool match(char c1, char c2){
switch(c1){
case ‘(‘:
return c2 == ‘)‘;
case ‘{‘:
return c2 == ‘}‘;
case ‘[‘:
return c2 ==‘]‘;
default:
return false;
}
}
};
来源： http://tool.oschina.net/highlight
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来自为知笔记(Wiz)
时间： 2024-08-10 17:17:44
