exam_code_for_408/code_tree_2017.cpp

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

typedef struct node {
    char data[10];
    struct node* left, * right;
}BTree;

void midQuation(BTree* T) {
    if (T != NULL && T->data[0] != '@') {
        char t = T->data[0];
        bool flag = false;
        flag = (t == '+' || t == '-' || t == '*' || t == '/');
        if (flag)printf("(");
        if (T->left != NULL)midQuation(T->left);//左子树递归
        printf("%c", T->data[0]);//打印当前节点
        if (T->right != NULL)midQuation(T->right);//右子树递归
        if (flag)printf(")");
    }
}

/**
 * 创建二叉树
 */
void createTree(BTree* node, char c[], int pos, int length) {
    if (pos < length) {//填入数据
        node->data[0] = c[pos];
        node->data[1] = '\0';
        node->left = (BTree*)malloc(sizeof(BTree));
        node->right = (BTree*)malloc(sizeof(BTree));
        createTree(node->left, c, pos * 2 + 1, length);
        createTree(node->right, c, pos * 2 + 2, length);
    }
}

int main() {
    BTree* a = (BTree*)malloc(sizeof(BTree));
    // createTree(a, "*+*abc-@@@@@@@d@@@@@@@@@@@@@@@@", 0, 31);//用@表示空节点
    createTree(a, "+*-ab@-@@@@@@cd@@@@@@@@@@@@@@@@", 0, 31);//用@表示空节点
    midQuation(a);
    return 0;
}