W3Schools 在线编辑器 - W3Schools 中文教程

Python

Java

#include <stdio.h>
#include <stdlib.h>

typedef struct TreeNode {
    char data;
    struct TreeNode* left;
    struct TreeNode* right;
} TreeNode;

TreeNode* createNewNode(char data) {
    TreeNode* newNode = (TreeNode*)malloc(sizeof(TreeNode));
    newNode->data = data;
    newNode->left = NULL;
    newNode->right = NULL;
    return newNode;
}

void preOrderTraversal(TreeNode* root) {
    if (root == NULL) {
        return;
    }
    printf("%c, ", root->data);
    preOrderTraversal(root->left);
    preOrderTraversal(root->right);
}

int main() {
    TreeNode* root = createNewNode('R');
    TreeNode* nodeA = createNewNode('A');
    TreeNode* nodeB = createNewNode('B');
    TreeNode* nodeC = createNewNode('C');
    TreeNode* nodeD = createNewNode('D');
    TreeNode* nodeE = createNewNode('E');
    TreeNode* nodeF = createNewNode('F');
    TreeNode* nodeG = createNewNode('G');

root->left = nodeA;
    root->right = nodeB;

nodeA->left = nodeC;
    nodeA->right = nodeD;

nodeB->left = nodeE;
    nodeB->right = nodeF;

nodeF->left = nodeG;

// Traverse
    preOrderTraversal(root);

free(nodeG);
    free(nodeF);
    free(nodeE);
    free(nodeB);
    free(nodeC);
    free(nodeD);
    free(nodeA);
    free(root);

return 0;
}

//C

public class Main {
    
    public static class TreeNode {
        String data;
        TreeNode left;
        TreeNode right;

public TreeNode(String data) {
            this.data = data;
            this.left = null;
            this.right = null;
        }
    }

public static void preOrderTraversal(TreeNode node) {
        if (node == null) {
            return;
        }
        System.out.print(node.data + ", ");
        preOrderTraversal(node.left);
        preOrderTraversal(node.right);
    }

public static void main(String[] args) {
        TreeNode root = new TreeNode("R");
        TreeNode nodeA = new TreeNode("A");
        TreeNode nodeB = new TreeNode("B");
        TreeNode nodeC = new TreeNode("C");
        TreeNode nodeD = new TreeNode("D");
        TreeNode nodeE = new TreeNode("E");
        TreeNode nodeF = new TreeNode("F");
        TreeNode nodeG = new TreeNode("G");

root.left = nodeA;
        root.right = nodeB;

nodeA.left = nodeC;
        nodeA.right = nodeD;

nodeB.left = nodeE;
        nodeB.right = nodeF;

nodeF.left = nodeG;

// Traverse
        preOrderTraversal(root);
    }
}

// Java