设计算法按前序次序打印二叉树中的叶子结点。 C语言

以下是一个基于递归的算法实现：

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

// 定义二叉树结构体
typedef struct TreeNode {
    int val;
    struct TreeNode* left;
    struct TreeNode* right;
} TreeNode;

// 创建二叉树
TreeNode* createTree() {
    TreeNode* root = (TreeNode*)malloc(sizeof(TreeNode));
    root->val = 1;
    root->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->val = 2;
    root->left->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->left->val = 4;
    root->left->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->right->val = 5;
    root->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->val = 3;
    root->right->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->left->val = 6;
    root->right->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->right->val = 7;
    return root;
}

// 前序遍历打印二叉树中的叶子节点
void printLeaves(TreeNode* root) {
    if (root == NULL) {
        return;
    }
    if (root->left == NULL && root->right == NULL) {
        printf("%d ", root->val);
    }
    printLeaves(root->left);
    printLeaves(root->right);
}

int main() {
    TreeNode* root = createTree();
    printLeaves(root);
    return 0;
}

注意，这里的二叉树是写死的，实际应用中需要根据具体需求动态创建二叉树。