c_cpp 获得二叉树的边缘和高度

Posted 2021-05-14

// https://www.jdoodle.com/online-compiler-c++
// https://www.youtube.com/watch?v=86g8jAQug04

#include <iostream>
#include <cstddef>
#include <queue>
#include <vector>

using namespace std;	

class Node{
    public:
        int data;
        Node *left;
        Node *right;
        Node(int d){
            data = d;
            left = NULL;
            right = NULL;
        }
};
class Solution{
    public:
  		Node* insert(Node* root, int data) {
            if(root == NULL) {
                return new Node(data);
            }
            else {
                Node* cur;
                if(data <= root->data){
                    cur = insert(root->left, data);
                    root->left = cur;
                }
                else{
                    cur = insert(root->right, data);
                    root->right = cur;
               }

               return root;
           }
        }
		int getHeight(Node* root){
          // Write your code here
          // we will read each level of the tree if all nodes are null then we have reached maximum height
            
            // if tree is empty return 0
            if (root == NULL || (!root->left && !root->right))
            {
                return 0;    
            }
            
            // create a queue and add the root node to it
            queue<Node *> treeNodeQueue;
            treeNodeQueue.push(root);
            
            int heightCount = 0;
            bool complete = false;
            
            while (!complete)
            {
                // nodeCount indicates how many nodes there are at the current height (e.g. there is 1 node at the root height, the next level could have 0,1 or 2 nodes...)
                int nodeCount = treeNodeQueue.size();
                
                //
                if (nodeCount == 0)
                {
                    // there are no nodes at this level so it is the end of the tree.
                    complete = true;
                    break;
                }

                // we have traversed one height level
                heightCount++;

                // continue as long as there is a node remaining to be processed at this level
                while (nodeCount > 0)
                {
                    // get the current node
                    Node *node = treeNodeQueue.front();
                    
                    // we start processing the current node
                    treeNodeQueue.pop();
                    
                    if (node->left != NULL)
                    {
                        // add the left child node
                        treeNodeQueue.push(node->left);
                    }
                    
                    if (node->right != NULL)
                    {
                        // add the right child node
                        treeNodeQueue.push(node->right);
                    }
                    
                    // node has been processed so lower the count
                    nodeCount--;
                }
            }
            
            // we -1 because we are counting the number of edges e.g. the root node is level 0.
            return heightCount -1; 
        }
}; //End of Solution

int main() {
    Solution myTree;
    Node *root = NULL;
    int t = 0;
    int count = 0;
    int data;
    vector<int> nodelist;
    
    t = 7;
    nodelist = {3, 5, 2, 1, 4, 6, 7};
    
    while(t-- > 0)
    {
        data = nodelist[count];
        root = myTree.insert(root, data);
        count++;
    }
    int height = myTree.getHeight(root);
    cout << height;

    return 0;
}