L2-004. 这是二叉搜索树吗？
参考博客
1 #include <cstdio>
2 #include <vector>
3 using namespace std;
4 bool isMirror;
5 vector<int> pre;
6 vector<int> post;
7 void getpost(int root, int tail) {
8 if(root > tail) return ;
9 int i = root + 1, j = tail;
10 if(!isMirror) {
11 while(i <= tail && pre[root] > pre[i]) i++;
12 while(j > root && pre[root] <= pre[j]) j--;
13 } else {
14 while(i <= tail && pre[root] <= pre[i]) i++;
15 while(j > root && pre[root] > pre[j]) j--;
16 }
17 if(i - j != 1) return ;
18 getpost(root + 1, j);///左
19 getpost(i, tail);///右
20 post.push_back(pre[root]);
21 }
22 int main() {
23 int n;
24 scanf("%d", &n);
25 pre.resize(n);
26 for(int i = 0; i < n; i++)
27 scanf("%d", &pre[i]);
28 getpost(0, n - 1);
29 if(post.size() != n) {
30 isMirror = true;
31 post.clear();
32 getpost(0, n - 1);
33 }
34 if(post.size() == n) {
35 printf("YES
%d", post[0]);
36 for(int i = 1; i < n; i++)
37 printf(" %d", post[i]);
38 } else {
39 printf("NO");
40 }
41 return 0;
42 }