What's wrong in my code? Why is it printing incorrect preorder traversal?

#1

#include
#include
using namespace std;
class node{
public:
int data;
node* left;
node* right;
node(int d){
data=d;
left=NULL;
right=NULL;
}
};
node* build_tree_from_array(int arr[],int s,int e)
{
if(s>e){
return NULL;
}
int mid=(s+e)/2;
node* root=new node(arr[mid]);
root->left=build_tree_from_array(arr,s,mid-1);
root->right=build_tree_from_array(arr,mid+1,e);
return root;
}
void preorder(node* root){
if(root==NULL){
return;
}
cout<data<<" ";
preorder(root->left);
preorder(root->right);
return;
}
void PrintRange(node* root,int a,int b){

if(root==NULL){
    return;
}

PrintRange(root->left,a,b);
if(root->data<=b and root->data>=a){
    cout<<root->data<<" ";
}
PrintRange(root->right,a,b);
return;

}
int main() {
int t;
cin>>t;
while(t–){
int n;
cin>>n;
int arr[n];
for(int i=0;i<n;i++)
{
cin>>arr[i];
}
sort(arr,arr+n);
node* root=build_tree_from_array(arr,0,n-1);
int b,c;
cin>>b>>c;

    cout<<"# Preorder : ";
    preorder(root);        
    cout<<endl<<"# Nodes within range are : ";
    PrintRange(root,b,c);
    cout<<endl;
}
return 0;

}#include
#include
using namespace std;
class node{
public:
int data;
node* left;
node* right;
node(int d){
data=d;
left=NULL;
right=NULL;
}
};
node* build_tree_from_array(int arr[],int s,int e)
{
if(s>e){
return NULL;
}
int mid=(s+e)/2;
node* root=new node(arr[mid]);
root->left=build_tree_from_array(arr,s,mid-1);
root->right=build_tree_from_array(arr,mid+1,e);
return root;
}
void preorder(node* root){
if(root==NULL){
return;
}
cout<data<<" ";
preorder(root->left);
preorder(root->right);
return;
}
void PrintRange(node* root,int a,int b){

if(root==NULL){
    return;
}

PrintRange(root->left,a,b);
if(root->data<=b and root->data>=a){
    cout<<root->data<<" ";
}
PrintRange(root->right,a,b);
return;

}
int main() {
int t;
cin>>t;
while(t–){
int n;
cin>>n;
int arr[n];
for(int i=0;i<n;i++)
{
cin>>arr[i];
}
sort(arr,arr+n);
node* root=build_tree_from_array(arr,0,n-1);
int b,c;
cin>>b>>c;

    cout<<"# Preorder : ";
    preorder(root);        
    cout<<endl<<"# Nodes within range are : ";
    PrintRange(root,b,c);
    cout<<endl;
}
return 0;

}

#2

hi @akshat_bharani
kindly save ur code on coding blocks ide and send link…
or u can refer my code -->

#3

code link: https://ide.codingblocks.com/s/644747

#4

hi @akshat_bharani

sort(arr,arr+n);

u are sorting all the nodes before that’s why ur code is giving incorrect o/p… just build the tree in order of nodes given… then compute the ans… refer my code i sent above…

#5

Okay sure got it. Thanks!!

1 Like
#6

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