zoukankan      html  css  js  c++  java
  • 03-树2. List Leaves (25) 二叉树的层序遍历

    03-树2. List Leaves (25)

    题目来源:http://www.patest.cn/contests/mooc-ds/03-%E6%A0%912

    Given a tree, you are supposed to list all the leaves in the order of top down, and left to right.

    Input Specification:

    Each input file contains one test case. For each case, the first line gives a positive integer N (<=10) which is the total number of nodes in the tree -- and hence the nodes are numbered from 0 to N-1. Then N lines follow, each corresponds to a node, and gives the indices of the left and right children of the node. If the child does not exist, a "-" will be put at the position. Any pair of children are separated by a space.

    Output Specification:

    For each test case, print in one line all the leaves' indices in the order of top down, and left to right. There must be exactly one space between any adjacent numbers, and no extra space at the end of the line.

    Sample Input:
    8
    1 -
    - -
    0 -
    2 7
    - -
    - -
    5 -
    4 6
    
    Sample Output:
    4 1 5

    题目大意: 通过输入节点数以及每个节点的左儿子和右儿子,从上到下打印出叶节点。
    题目关键:要理解输入的第几行就是代表该节点的值为几。例如样例输入中第0行的1 -代表值为0的节点左孩子的值为1,即指向第1行,右孩子为空(-1)
    树模型如下:


    代码如下:
     1 #include <cstdio>
     2 #include <cctype>
     3 
     4 #define N 10
     5 
     6 typedef struct Node
     7 {
     8     int data, left, right;
     9 } TreeNode;
    10 TreeNode node[N];
    11 TreeNode Queue[N];          //数组实现队列
    12 
    13 int first = -1, last = -1;
    14 
    15 void Push(TreeNode tn);
    16 TreeNode Pop();
    17 void printLeaves(int root, int n);
    18 
    19 int charToInt(char ch);
    20 
    21 int main()
    22 {
    23     int n;
    24     bool isRoot[N];
    25     int root;
    26 
    27     scanf("%d
    ", &n);
    28     for (int i = 0; i < n; i++)
    29         isRoot[i] = 1;
    30     for (int i = 0; i < n; i++)
    31     {
    32         char cLeft, cRight;
    33         scanf("%c %c", &cLeft, &cRight);
    34         getchar();      //读取缓存区的回车符
    35         node[i].left = charToInt(cLeft);
    36         node[i].right = charToInt(cRight);
    37         node[i].data = i;
    38         //一个节点的左孩子和右孩子一定不是根节点
    39         if (node[i].left != -1)
    40             isRoot[node[i].left] = 0;
    41         if (node[i].right != -1)
    42             isRoot[node[i].right] = 0;
    43     }
    44     //找到根节点
    45     for (int i = 0; i < n; i++)
    46     {
    47         if (isRoot[i])
    48         {
    49             root = i;
    50             break;
    51         }
    52     }
    53     printLeaves(root, n);
    54 
    55     return 0;
    56 }
    57 
    58 void Push(TreeNode treeNode)
    59 {
    60     Queue[++last] = treeNode;
    61 }
    62 
    63 TreeNode Pop()
    64 {
    65     return Queue[++first];
    66 }
    67 
    68 //层序遍历树节点并打印出叶节点:队列实现
    69 void printLeaves(int root, int n)
    70 {
    71     int leaves[N];
    72     int k = 0;
    73     Push(node[root]);
    74     for (int i = 0; i < n; i++)
    75     {
    76         TreeNode tn = Pop();
    77         //左孩子和右孩子都不存在时,将叶节点的值保存到数组中,便于格式化打印
    78         if (tn.left == -1 && tn.right == -1)
    79             leaves[k++] = tn.data;
    80         if (tn.left != -1)
    81             Push(node[tn.left]);
    82         if (tn.right != -1)
    83             Push(node[tn.right]);
    84     }
    85     for (int i = 0; i < k-1; i++)
    86         printf("%d ", leaves[i]);
    87     printf("%d
    ", leaves[k-1]);
    88 }
    89 
    90 int charToInt(char ch)
    91 {
    92     if (isdigit(ch))
    93         return ch - '0';
    94     else
    95         return -1;
    96 }

  • 相关阅读:
    如何在Ubuntu18.04(Bionic Beaver)系统安装Teamviewer远程控制软件
    glVertexAttribPointer 用法简介
    OpenGL ES SL 3.0规范中以前的attribute改成了in varying改成了out
    C++多线程中用临界区控制全局变量的访问冲突问题
    fatal error LNK1169: 找到一个或多个多重定义的符号或多个.c/.cpp文件想同时调用定义在.h文件里面的全局变量,防止重定义变量问题。
    WaitForSingleObject的详细用法
    [转]Win7 + Ubuntu 18.04 LTS (Bionic Beaver)双系统安装方法
    [Android Pro] Android打包一个Apk后,如何查看它的VersionCode、VersionName 等等。
    [Android] 查看Android中的AlarmManager事件
    [Android Pro] proguard
  • 原文地址:https://www.cnblogs.com/llhthinker/p/4748676.html
Copyright © 2011-2022 走看看