Unknown array size

#1

How can I input an array of unknown size?

#2

you need not to store this in an array
take input make a node and insert in tree

you can see this

node* BuildTree(){
    int d;cin>>d;
    if(d==-1)return NULL:
    node*nn=new node(d);
    nn->left=BuildTree();
    nn->right=BuildTree();
    return   nn;
}
#3

hi @rohanmd07

i have seen just now that it is mention that input format is in inorder

Input Format
Level order input for the binary tree will be given.

so correct way to take input is

int i=0
    queue<node*>q;
    q.push(arr[i++]);
    while(!q.empty()){
        node*temp=q.front();
        q.pop();
        else{
            int leftchild=arr[i++],rightchild=arr[i++];
            if(leftchild!=-1){
                temp->left=new node(leftchild);
                q.push(temp->left);
            }
            else temp->left=NULL;
            if(rightchild!=-1){
                temp->right=new node(rightchild);
                q.push(temp->right);
            }
            else temp->right=NULL;
        }
    }
#4

to take input of unknown size array use can do

int arr[1000];
    int x;
    int i=0
    while(cin>>x){
      arr[i]=x;
      i++;
    }