Search key in B-Tree

Author: rishab-raina

Search B-Tree

@@ -0,0 +1,184 @@
+// Searching a key on a B-tree in C++
+
+#include <iostream>
+using namespace std;
+
+class TreeNode {
+  int *keys;
+  int t;
+  TreeNode **C;
+  int n;
+  bool leaf;
+
+   public:
+  TreeNode(int temp, bool bool_leaf);
+
+  void insertNonFull(int k);
+  void splitChild(int i, TreeNode *y);
+  void traverse();
+
+  TreeNode *search(int k);
+
+  friend class BTree;
+};
+
+class BTree {
+  TreeNode *root;
+  int t;
+
+   public:
+  BTree(int temp) {
+    root = NULL;
+    t = temp;
+  }
+
+  void traverse() {
+    if (root != NULL)
+      root->traverse();
+  }
+
+  TreeNode *search(int k) {
+    return (root == NULL) ? NULL : root->search(k);
+  }
+
+  void insert(int k);
+};
+
+TreeNode::TreeNode(int t1, bool leaf1) {
+  t = t1;
+  leaf = leaf1;
+
+  keys = new int[2 * t - 1];
+  C = new TreeNode *[2 * t];
+
+  n = 0;
+}
+
+void TreeNode::traverse() {
+  int i;
+  for (i = 0; i < n; i++) {
+    if (leaf == false)
+      C[i]->traverse();
+    cout << " " << keys[i];
+  }
+
+  if (leaf == false)
+    C[i]->traverse();
+}
+
+TreeNode *TreeNode::search(int k) {
+  int i = 0;
+  while (i < n && k > keys[i])
+    i++;
+
+  if (keys[i] == k)
+    return this;
+
+  if (leaf == true)
+    return NULL;
+
+  return C[i]->search(k);
+}
+
+void BTree::insert(int k) {
+  if (root == NULL) {
+    root = new TreeNode(t, true);
+    root->keys[0] = k;
+    root->n = 1;
+  } else {
+    if (root->n == 2 * t - 1) {
+      TreeNode *s = new TreeNode(t, false);
+
+      s->C[0] = root;
+
+      s->splitChild(0, root);
+
+      int i = 0;
+      if (s->keys[0] < k)
+        i++;
+      s->C[i]->insertNonFull(k);
+
+      root = s;
+    } else
+      root->insertNonFull(k);
+  }
+}
+
+void TreeNode::insertNonFull(int k) {
+  int i = n - 1;
+
+  if (leaf == true) {
+    while (i >= 0 && keys[i] > k) {
+      keys[i + 1] = keys[i];
+      i--;
+    }
+
+    keys[i + 1] = k;
+    n = n + 1;
+  } else {
+    while (i >= 0 && keys[i] > k)
+      i--;
+
+    if (C[i + 1]->n == 2 * t - 1) {
+      splitChild(i + 1, C[i + 1]);
+
+      if (keys[i + 1] < k)
+        i++;
+    }
+    C[i + 1]->insertNonFull(k);
+  }
+}
+
+void TreeNode::splitChild(int i, TreeNode *y) {
+  TreeNode *z = new TreeNode(y->t, y->leaf);
+  z->n = t - 1;
+
+  for (int j = 0; j < t - 1; j++)
+    z->keys[j] = y->keys[j + t];
+
+  if (y->leaf == false) {
+    for (int j = 0; j < t; j++)
+      z->C[j] = y->C[j + t];
+  }
+
+  y->n = t - 1;
+  for (int j = n; j >= i + 1; j--)
+    C[j + 1] = C[j];
+
+  C[i + 1] = z;
+
+  for (int j = n - 1; j >= i; j--)
+    keys[j + 1] = keys[j];
+
+  keys[i] = y->keys[t - 1];
+  n = n + 1;
+}
+
+int main() {
+  BTree t(3);
+  t.insert(8);
+  t.insert(9);
+  t.insert(10);
+  t.insert(11);
+  t.insert(15);
+  t.insert(16);
+  t.insert(17);
+  t.insert(18);
+  t.insert(20);
+  t.insert(23);
+
+  cout << "The B-tree is: ";
+  t.traverse();
+
+  int k = 10;
+  (t.search(k) != NULL) ? cout << endl
+                 << k << " is found"
+              : cout << endl
+                 << k << " is not Found";
+
+  k = 2;
+  (t.search(k) != NULL) ? cout << endl
+                 << k << " is found"
+              : cout << endl
+                 << k << " is not Found\n";
+}