九度oj 1523 从上往下打印二叉树

原题链接：http://ac.jobdu.com/problem.php?pid=1523

建树，再层次遍历bfs。为了找根方便些，加了father指针。。。

如下：

 1 #include<algorithm>

 2 #include<iostream>

 3 #include<cstdlib>

 4 #include<cstring>

 5 #include<cstdio>

 6 #include<vector>

 7 #include<queue>

 8 using std::queue;

 9 using std::vector;

10 using std::cin;

11 const int Max_N = 1100;

12 struct Node{

13     int v;

14     Node *f, *ch[2];

15     inline void set(int _v = 0, Node *p = NULL){

16         v = _v, f = ch[0] = ch[1] = p;

17     }

18     inline void link(Node *x, bool d){

19         ch[d] = x;

20         x->f = this;

21     }

22 };

23 struct BinaryTree{

24     Node *tail, *root, *null;

25     Node stack[Max_N], *ptr[Max_N];

26     void init(){

27         tail = &stack[0];

28         null = tail++;

29         null->set();

30         root = null;

31     }

32     inline Node *newNode(int v){

33         Node *p = tail++;

34         p->set(v, null);

35         return p;

36     }

37     inline void gogo(int n){

38         char c;

39         int i, v, a, b;

40         for (i = 1; i <= n; i++){

41             scanf("%d", &v);

42             ptr[i] = newNode(v);

43         }

44         for (i = 1; i <= n; i++){

45             cin >> c;

46             if (c == 'd'){

47                 scanf("%d %d", &a, &b);

48                 ptr[i]->link(ptr[a], 0);

49                 ptr[i]->link(ptr[b], 1);

50             } else if (c == 'l'){

51                 scanf("%d", &a);

52                 ptr[i]->link(ptr[a], 0);

53             } else if (c == 'r'){

54                 scanf("%d", &b);

55                 ptr[i]->link(ptr[b], 1);

56             } else {

57                 ;

58             }

59             if (ptr[i]->f == null) root = ptr[i];

60         }

61     }

62     inline void bfs(){

63         queue<Node *> que;

64         vector<int> ans;

65         que.push(root);

66         while (!que.empty()){

67             Node *x = que.front();

68             que.pop();

69             ans.push_back(x->v);

70             if (x->ch[0] != null) que.push(x->ch[0]);

71             if (x->ch[1] != null) que.push(x->ch[1]);

72         }

73         int n = ans.size();

74         for (int i = 0; i < n; i++){

75             printf("%d%c", ans[i], i < n - 1 ? ' ' : '\n');

76         }

77     }

78 }tree;

79 int main(){

80 #ifdef LOCAL

81     freopen("in.txt", "r", stdin);

82     freopen("out.txt", "w+", stdout);

83 #endif

84     int n;

85     while (~scanf("%d", &n)){

86         tree.init(), tree.gogo(n), tree.bfs();

87     }

88     return 0;

89 }

View Code