C语言实现二叉树叶子结点统计：原理与代码解析

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

typedef char ElemType;

// 定义二叉树结点结构
typedef struct BTNode {
    ElemType data;
    struct BTNode *left;
    struct BTNode *right;
}BTNode, *BiTree;

/**
 * 创建二叉树
 * @param BT 指向树结点的指针的指针
 * @description 按照先序序列输入字符，空格表示空节点
 */
void createBTNode(BiTree &BT) {
    ElemType ch;
    scanf("%c", &ch);
    if(ch == ' ') {
        BT = NULL;
    } else {
        BT = (BTNode*)malloc(sizeof(BTNode));
        BT->data = ch;
        createBTNode(BT->left);   // 递归创建左子树
        createBTNode(BT->right);  // 递归创建右子树
    }
}

/**
 * 先序遍历打印二叉树
 */
void printDLR(BiTree BT) {
    if(BT) {
        printf("%c ", BT->data);
        printDLR(BT->left);
        printDLR(BT->right);
    }
}

/**
 * 统计叶子结点个数
 * @param BT 当前访问的结点
 * @param count 指向计数器的指针
 */
void countLeaves(BiTree BT, int &count) {
    if(BT) {
        // 如果是叶子结点，计数器加1
        if(BT->left == NULL && BT->right == NULL) {
            count++;
        } else {
            // 否则继续遍历左右子树
            countLeaves(BT->left, count);
            countLeaves(BT->right, count);
        }
    }
}

int main() {
    BiTree BT;
    int count = 0;
    
    printf("请输入二叉树结点（先序，空格表示空）:\n");
    createBTNode(BT);
    
    printf("\n先序遍历结果: ");
    printDLR(BT);
    
    countLeaves(BT, count);
    printf("\n二叉树叶子结点的个数: %d\n", count);
    
    return 0;
}