题解 | #二叉树遍历#

#include "cstdio"
#include "string"
using namespace std;
struct TreeNode{
    char data;
    TreeNode * leftChild;
    TreeNode * rightChild;
};
TreeNode * build(int &i,string preorder){
    //返回本棵子树根节点地址
    char c =preorder[i];
    ++i;
    if (c=='#'){
        return NULL;
    } else{
        TreeNode * pNewNode = new TreeNode;
        pNewNode->data =c;
        pNewNode->leftChild= build(i,preorder);
        pNewNode->rightChild= build(i,preorder);
        return pNewNode;
    }
}
void InOrder(TreeNode *root){
    if (root==NULL){
        return;
    }
    InOrder(root->leftChild);
    printf("%c ",root->data);
    InOrder(root->rightChild);

}
int main(){
    char preorder[100];
    int i=0;
    while (scanf("%s",preorder)!=EOF){
        TreeNode * root = build(i,preorder);
        InOrder(root);
    }
}