Sword To Offer 023 - 二叉搜索树的后序遍历序列

class Solution {
private:
    bool Verify(const vector<int>& sequence, int left, int right) {
        if(sequence.empty()) {
            return false;
        }
        int index = right - 1;
        for(; index >= left; index--) {
            if(sequence[index] < sequence[right]) {
                break;
            }
        }
        if(index < left) {
            return true;
        }
        for(int i = index + 1; i < right; i++) {
            if(sequence[i] < sequence[right]) {
                return false;
            }
        }
        for(int i = left; i <= index; i++) {
            if(sequence[i] > sequence[right]) {
                return false;
            }
        }
        return Verify(sequence, left, index) && Verify(sequence, index + 1, right - 1);
    }
public:
    bool VerifySquenceOfBST(const vector<int> &sequence) {
        return Verify(sequence, 0, sequence.size() - 1);
    }
};