if(stack2.empty()||stack2.top()>=op[i][1])判空放在||后面会报错

class Solution {
public:
    /**
     * return a array which include all ans for op3
     * @param op int整型vector<vector<>> operator
     * @return int整型vector
     */
    vector<int> getMinStack(vector<vector<int> >& op) {
        // write code here
        int size=op.size();
        stack<int>stack1;
        stack<int>stack2;
        vector<int>ret;
        for(int i=0;i<size;i++)
        {
                if(op[i][0]==1)
                {
                    stack1.push(op[i][1]);
                    if(stack2.empty()||stack2.top()>=op[i][1])
                        stack2.push(op[i][1]);
                }
                else if(op[i][0]==2)
                {
                    if(!stack1.empty())
                    {
                        if(stack2.top()==stack1.top()) stack2.pop();
                        stack1.pop();
                    }
                }
                else
                {
                    ret.push_back(stack2.top());
                }
        }
        return ret;
    }
};