Sicily 1310：Right-Heavy Tree（二叉搜索树）

#include<bits/stdc++.h>
using namespace std;


struct Node{
    int val;
    Node *left;
    Node *right;
    Node(){
        val = 0;
        left = NULL;
        right = NULL;
    }
}arr[200000];

void insert(Node *root, int a){
    if(a > root->val){
        if(root->right != NULL){
            insert(root->right, a);
        }
        else{
            Node* next = new Node;
            next->val = a;
            root->right = next;
            return;
        }
    }
    else{
        if(root->left != NULL){
            insert(root->left, a);
        }
        else{
            Node *next = new Node;
            next->val = a;
            root->left = next;
            return;
        }
    }
}

void inOrder(Node *root){
    if(root->left != NULL){
        inOrder(root->left);
    }
    printf(" %d", root->val);
    if(root->right != NULL){
        inOrder(root->right);
    }
}
void preOrder(Node *root){
    printf(" %d", root->val);
    if(root->left != NULL){
        preOrder(root->left);
    }
    if(root->right != NULL){
        preOrder(root->right);
    }   
}
void posOrder(Node *root){
    if(root->left != NULL){
        posOrder(root->left);
    }
    if(root->right != NULL){
        posOrder(root->right);
    }   
    printf(" %d", root->val);
}

void init(int n){
    for(int i = 0; i < n+1; i++){
        arr[i].val = 0;
        arr[i].left = arr[i].right = NULL;
    }
}
int main(){
    int n;
    int first = 1;
    while(cin >> n){
        int a;
        init(n);
        if(n > 0){
            scanf("%d", &arr[0].val);
            arr[0].left = arr[0].right = NULL;
        }
        for(int i = 1; i < n; i++){
            scanf("%d", &a);
            arr[i].val = a;
            arr[i].left = arr[i].right = NULL;
            Node *tmp = &arr[0];
            Node *last;
            while(tmp != NULL){
                last = tmp;
                if(a > tmp->val){
                    tmp = tmp->right;
                }
                else{
                    tmp = tmp->left;
                }
            }
            if(a > last->val){
                last->right = &arr[i];
            }
            else{
                last->left = &arr[i];
            }
        }
        
        if(first == 1){
            first = 0;
        }
        else{
            cout << endl;
        }
        printf("Inorder:");
        if(arr[0].val != 0)inOrder(&arr[0]);
        printf("\n");
        printf("Preorder:");
        if(arr[0].val != 0)preOrder(&arr[0]);
        printf("\n");
        printf("Postorder:");
        if(arr[0].val != 0)posOrder(&arr[0]);
        printf("\n");

    }
}