1 /*************************************************************************
2 > File Name: 22_SequenceOfBST.cpp
3 > Author: Juntaran
4 > Mail: JuntaranMail@gmail.com
5 > Created Time: 2016年08月30日 星期二 20时34分33秒
6 ************************************************************************/
7
8 #include <stdio.h>
9 #include <stdlib.h>
10
11 // 判断一个数组是不是某个二叉搜索树的后序遍历
12 bool isSequenceOfBST(int* sequence, int length)
13 {
14 if (sequence==NULL || length<=0)
15 return false;
16
17 int root = sequence[length-1];
18
19 int i, j;
20
21 // 二叉搜索树的左子树都小于根
22 for (i = 0; i < length-1; ++i)
23 {
24 if (sequence[i] > root)
25 break;
26 }
27
28 // 二叉搜索树的右子树都大于根
29 for (j = i; j < length-1; ++j)
30 {
31 if (sequence[j] < root)
32 return false;
33 }
34
35 // 递归判断左子树是不是二叉搜索树
36 bool left = true;
37 if (i > 0)
38 left = isSequenceOfBST(sequence, i);
39
40 // 递归判断右子树是不是二叉搜索树
41 bool right = true;
42 if (i < length-1)
43 right = isSequenceOfBST(sequence+i, length-i-1);
44
45 return (left && right);
46 }
47
48 int main()
49 {
50 int sequence1[] = {5,7,6,9,11,10,8};
51 int sequence2[] = {7,4,5,6};
52 bool ret1 = isSequenceOfBST(sequence1, 7);
53 bool ret2 = isSequenceOfBST(sequence2, 4);
54 if (ret1 == true)
55 printf("ret1 is true\n");
56 else
57 printf("ret1 is false\n");
58
59 if (ret2 == true)
60 printf("ret2 is true\n");
61 else
62 printf("ret2 is false\n");
63
64 return 0;
65 }
