PAT 1099. Build A Binary Search Tree (30)

题目地址： http://www.patest.cn/contests/pat-a-practise/1099

单纯的数据结构题目

想到中序遍历的BST是有序的， 中序插入数， 层序遍历输出就可以了，这个题目为什么是30分呢， 纳闷

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<queue>
 4 #include<algorithm>
 5 
 6 using namespace std;
 7 
 8 const int MAX_NODES = 1000;
 9 struct Node {
10         int lchild;
11         int rchild;
12         int num;
13 } nodes[MAX_NODES];
14 int len = 0;
15 
16 int nums[MAX_NODES];
17 int num_index = 0;
18 void in_order(int root) {
19         if (root != -1) {
20                 in_order(nodes[root].lchild);
21                 nodes[root].num = nums[num_index++];
22                 in_order(nodes[root].rchild);
23         }
24 }
25 
26 queue<int> q;
27 void level_order(int root) {
28         num_index = 0;
29         while(!q.empty()) q.pop(); //我不知道怎么清空队列， 只能这样了， 哈哈
30         q.push(root);
31         while(!q.empty()) {
32                 int x = q.front();
33                 q.pop();
34                 nums[num_index++] = nodes[x].num;
35                 if (nodes[x].lchild != -1)
36                         q.push(nodes[x].lchild);
37                 if (nodes[x].rchild != -1) 
38                         q.push(nodes[x].rchild);
39         }
40 }
41 
42 void debug_print() {
43         cout << "===============debug==========================" << endl;
44         for (int i = 0; i < len; ++i) {
45                 cout << nodes[i].num << endl;
46         }
47         cout << "================debug end =====================" << endl;
48 }
49 
50 int main() {
51         while(cin >> len) {
52                 for (int i = 0; i < len; ++i) {
53                         cin >> nodes[i].lchild >> nodes[i].rchild;
54                 }
55                 for (int i = 0; i < len; ++i) {
56                         cin >> nums[i];
57                 }
58                 sort(nums, nums + len);
59                 in_order(0);
60                 //debug_print();
61                 //cout << "post_order done" << endl;
62                 level_order(0);
63                 //cout << "level_order done" << endl;
64                 cout << nums[0];
65                 for (int i = 1; i < len; ++i) {
66                         cout << " " << nums[i];
67                 }
68                 cout << endl;
69         }
70         return 0;
71 }

 

posted @ 2015-04-11 00:51  ACSeed  Views(258)  Comments(0)    收藏  举报