Range Tree in C - Sanfoundry

This is a C Program to implement range tree.
range Tree: The idea is to augment a self-balancing Binary Search Tree (BST) like Red Black Tree, AVL Tree, etc to maintain set of ranges so that all operations can be done in order log n time.

Here is source code of the C Program to Implement Range Tree. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

```
#include <stdio.h>
```
```
#include <math.h>
```
```
 
```
```
// Structure to represent an range
```
```
struct range {
```
```
    int low, high;
```
```
};
```
```
 
```

// Structure to represent a node in range Search Tree

```
struct RTNode {
```

    range *i; // 'i' could also be a normal variable

```
    int max;
```
```
    RTNode *left, *right;
```
```
};
```
```
 
```

// A utility function to create a new range Search Tree Node

```
RTNode * newNode(range i) {
```
```
    RTNode *temp = new RTNode;
```
```
    temp->i = new range(i);
```
```
    temp->max = i.high;
```
```
    temp->left = temp->right = NULL;
```
```
}
```
```
;
```
```
 
```

// A utility function to insert a new range Search Tree Node

// This is similar to BST Insert.  Here the low value of range

```
// is used tomaintain BST property
```
```
RTNode *insert(RTNode *root, range i) {
```

    // Base case: Tree is empty, new node becomes root

```
    if (root == NULL)
```
```
        return newNode(i);
```
```
 
```
```
    // Get low value of range at root
```
```
    int l = root->i->low;
```
```
 
```

    // If root's low value is smaller, then new range goes to

```
    // left subtree
```
```
    if (i.low < l)
```

        root->left = insert(root->left, i);

```
 
```

    // Else, new node goes to right subtree.

```
    else
```

        root->right = insert(root->right, i);

```
 
```

    // Update the max value of this ancestor if needed

```
    if (root->max < i.high)
```
```
        root->max = i.high;
```
```
 
```
```
    return root;
```
```
}
```
```
 
```

// A utility function to check if given two ranges overlap

```
bool doOVerlap(range i1, range i2) {
```

    if (i1.low <= i2.high && i2.low <= i1.high)

```
        return true;
```
```
    return false;
```
```
}
```
```
 
```

// The main function that searches a given range i in a given

```
// range Tree.
```

range *rangeSearch(RTNode *root, range i) {

```
    // Base Case, tree is empty
```
```
    if (root == NULL)
```
```
        return NULL;
```
```
 
```

    // If given range overlaps with root

```
    if (doOVerlap(*(root->i), i))
```
```
        return root->i;
```
```
 
```

    // If left child of root is present and max of left child is

    // greater than or equal to given range, then i may

    // overlap with an range is left subtree

    if (root->left != NULL && root->left->max >= i.low)

        return rangeSearch(root->left, i);

```
 
```

    // Else range can only overlap with right subtree

```
    return rangeSearch(root->right, i);
```
```
}
```
```
 
```
```
void inorder(RTNode *root) {
```
```
    if (root == NULL)
```
```
        return;
```
```
 
```
```
    inorder(root->left);
```
```
 
```

    cout << "[" << root->i->low << ", " << root->i->high << "]" << " max = "

```
            << root->max << endl;
```
```
 
```
```
    inorder(root->right);
```
```
}
```
```
 
```

// Driver program to test above functions

```
int main() {
```

    // Let us create range tree shown in above figure

    range ints[] = { { 15, 20 }, { 10, 30 }, { 17, 19 }, { 5, 20 },

```
            { 12, 15 }, { 30, 40 } };
```

    int n = sizeof(ints) / sizeof(ints[0]);

```
    RTNode *root = NULL;
```
```
    for (int i = 0; i < n; i++)
```
```
        root = insert(root, ints[i]);
```
```
 
```

    printf("Inorder traversal of constructed range Tree is\n");

```
    inorder(root);
```
```
 
```
```
    range x = { 6, 7 };
```
```
 
```

    printf("\nSearching for range [%d, %d]", x.low, x.high);

```
    range *res = rangeSearch(root, x);
```
```
    if (res == NULL)
```

        printf("\nNo Overlapping range");

```
    else
```

        printf("\nOverlaps with [%d, %d]", res->low, res->high);

```
}
```

Output:

$ gcc RangeTree.c
$ ./a.out
 
Inorder traversal of constructed range Tree is
[5, 20] max = 20
[10, 30] max = 30
[12, 15] max = 15
[15, 20] max = 40
[17, 19] max = 40
[30, 40] max = 40
 
Searching for range [6,7]
Overlaps with [5, 20]

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