二叉搜索树的后续遍历序列(边界条件怎样确定)

解法1：

class Solution {
public:
    bool VerifySquenceOfBST(vector<int> sequence) {
        return bst(sequence,0,sequence.size()-1);
    }
    bool bst(vector<int>& sequence,int begin,int end)
    {
        if(sequence.empty()||begin>end)//是否需要判断begin>end
            return false;
        int i=begin;
        for(;i<end;i++)
        {
            if(sequence[i]>sequence[end])
            {
                break;
            }
        }
        for(int j = i;j<end;j++)
        {
            if(sequence[j]<sequence[end])
            {
                return false;
            }
        }
        bool left = true;
        if(i>begin)
        {
            left = bst(sequence,begin,i-1);
        }
        bool right = true;
        if(i<end-1)
        {
            right =bst(sequence,i,end-1);
        }
        return left&right;
    }
};