输入一个整数数组，判断该数组是不是某二叉搜索树的后序遍历的结果。如果是则输出Yes,否则输出No。假设输入的数组的任意两个数字都互不相同。
若是，则对其任意子树的序列，其末尾元素大于序列中的前若干个元素，而小于其他元素。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
| class Solution {
public:
bool VerifySquenceOfBST(vector<int> sequence) {
if (sequence.size() == 0)
{
return false;
}
else if (sequence.size() == 1)
{
return true;
}
else
{
const int root = sequence[sequence.size() - 1];
bool is_left_part = true;
int first_right_index = -1;
for (int i = 0; i < sequence.size(); i++)
{
if (is_left_part)
{
if (sequence[i] > root)
{
first_right_index = i;
is_left_part = false;
}
}
else
{
if (sequence[i] < root)
{
return false;
}
}
}
if (first_right_index <= 0)
{
return VerifySquenceOfBST(vector<int>(sequence.begin(), sequence.begin() + sequence.size() - 1));
}
else
{
return VerifySquenceOfBST(vector<int>(sequence.begin(), sequence.begin() + first_right_index)) \
&& VerifySquenceOfBST(vector<int>(sequence.begin() + first_right_index, sequence.end()));
}
}
}
};
|