class Solution {
public:
bool isPopOrder(vector<int> pushV,vector<int> popV) {
if (pushV.size() != popV.size()) return false;
stack<int> stk;
int k = 0;
for (auto x : pushV){
stk.push(x);
// 注意stk中不能为空的条件
while(stk.size() && stk.top() == popV[k]){
stk.pop();
k++;
}
}
return stk.empty();
}
};