pat甲级1043

1043 Is It a Binary Search Tree (25 point(s))

原地址

思路:

  1. 模板题。树的先序、后序遍历

代码:

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
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81

using namespace std;
const int maxn = 1e5+5;
const int INF = 0x3f3f3f3f;
const double eps = 1e-6;
const int MOD = 1000000007;
typedef long long ll;
#define pb push_back

vector<int> orign,pre,post,preM,postM;
struct {
int data;
node *left,*right;
};
void insert(node *&r,int data) {
if (!r) {
r = new node;
r->left = r->right = NULL;
r->data = data;
return;
}
if (data < r->data) {
insert(r->left,data);
} else {
insert(r->right,data);
}
}
void preOrder(node *r,vector<int> &v) {
if (!r) return;
v.pb(r->data);
preOrder(r->left,v);
preOrder(r->right,v);
}
void mirrorPreOrder(node *r,vector<int> &v) {
if (!r) return;
v.pb(r->data);
mirrorPreOrder(r->right,v);
mirrorPreOrder(r->left,v);
}
void postOrder(node *r,vector<int> &v) {
if (!r) return;
postOrder(r->left,v);
postOrder(r->right,v);
v.pb(r->data);
}
void mirrorPostOrder(node *r,vector<int> &v) {
if (!r) return;
mirrorPostOrder(r->right,v);
mirrorPostOrder(r->left,v);
v.pb(r->data);
}
int main() {
#ifdef ONLIGE_JUDGE
#else
freopen("H:\in.txt","r",stdin);
#endif
int n,t;
node *root = NULL;
cin >> n;
for (int i = 0; i < n; ++i) {
cin >> t;
orign.pb(t);
insert(root,t);
}
preOrder(root,pre);
mirrorPreOrder(root,preM);
if (orign == pre) {
printf("YESn");
postOrder(root,post);
for (int i = 0; i < post.size(); ++i)
i ? printf(" %d",post[i]) : printf("%d",post[i]);
} else if (orign == preM) {
printf("YESn");
mirrorPostOrder(root,postM);
for (int i = 0; i < postM.size(); ++i)
i ? printf(" %d",postM[i]) : printf("%d",postM[i]);
} else {
printf("NOn");
}
return 0;
}