栈的压入、弹出序列

class Solution {
public:
    bool IsPopOrder(vector<int> pushV, vector<int> popV)
    {
        stack<int> res;
        int i = 0, j = 0;
        res.push(pushV[i++]);
        while (!res.empty())
        {
            if (res.top() != popV[j])
            {

                if (i == pushV.size())
                    return false;

                res.push(pushV[i++]);
            }
            else
            {
                res.pop();
                ++j;
            }
        }
        return true;
    }
};