Binary tree traversal

The following procedures implement the pre-order, middle-order, and post-order traversal of Binary Trees respectively!

#include<iostream>#include<cstring>#include<queue>using namespace std;struct LNode{    char data;    LNode *lchild;    LNode *rchild;};#define N 1000void inorder(LNode *root){    if(root){        inorder(root->lchild);        cout<<root->data<<" ";        inorder(root->rchild);    }}void preorder(LNode *root){    if(root){        cout<<root->data<<" ";        preorder(root->lchild);        preorder(root->rchild);    }}void postorder(LNode *root){    if(root){        postorder(root->lchild);        postorder(root->rchild);        cout<<root->data<<" ";    }}void leverorder(LNode *root){    queue<LNode *> my_queue;    my_queue.push(root);    while(!my_queue.empty()){        LNode *p=my_queue.front();        my_queue.pop();        cout<<p->data<<" ";        if(p->lchild!=NULL)            my_queue.push(p->lchild);        if(p->rchild!=NULL)            my_queue.push(p->rchild);    }}int main(){    char ldate[N];    cin>>ldate;    char flag[N];    int i;    flag[0]='0';    char ch='A';    for(i=1;i<strlen(ldate);i+=2){        flag[i]=flag[i+1]=ch;        ++ch;    }    flag[i-1]='\0';    i=0;    LNode *tree[N];    while(i<strlen(flag)){        tree[i]=new LNode();        tree[i]->data=ldate[i];        tree[i]->lchild=NULL;        tree[i]->rchild=NULL;        i++;    }          LNode *root=new LNode;    for(i=0;i<strlen(flag);++i){        if(flag[i]=='0'){            root=tree[i];            continue;        }                  int j;        for(j=0;j<strlen(ldate);++j){            if(tree[j]->data==flag[i]){                if(tree[j]->lchild==NULL)                    tree[j]->lchild=tree[i];                else                    if(tree[j]->rchild==NULL)                        tree[j]->rchild=tree[i];            }        }    }    LNode *p=root;    inorder(p);    cout<<endl;    p=root;    preorder(p);    cout<<endl;    p=root;    postorder(p);    cout<<endl;    p=root;    leverorder(p);    cout<<endl;    return 0;}

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