B+tree.cpp

#include<iostream>
using namespace std;
struct BTree//node declaration 
{
   int *d;
   BTree **child_ptr;
   bool l;
   int n;
}*r = NULL, *np = NULL, *x = NULL;

BTree* init()//creation of node {
   int i;
   np = new BTree;
   np->d = new int[6];//order 6
   np->child_ptr = new BTree *[7];
   np->l = true;
   np->n = 0;
   for (i = 0; i < 7; i++) {
      np->child_ptr[i] = NULL;
   }
   return np;
}

void traverse(BTree *p)//traverse the tree {
   cout<<endl;
   int i;
   for (i = 0; i < p->n; i++) {
      if (p->l == false) {
         traverse(p->child_ptr[i]);
      }
      cout << " " << p->d[i];
   }
   if (p->l == false) {
      traverse(p->child_ptr[i]);
   }
   cout<<endl;
}

void sort(int *p, int n)//sort the tree {
   int i, j, t;
   for (i = 0; i < n; i++) {
      for (j = i; j <= n; j++) {
         if (p[i] >p[j]) {
            t = p[i];
            p[i] = p[j];
            p[j] = t;
         }
      }
   }
}

int split_child(BTree *x, int i) {
   int j, mid;
   BTree *np1, *np3, *y;
   np3 = init();//create new node
   np3->l = true;
   if (i == -1) {
      mid = x->d[2];//find mid
      x->d[2] = 0;
      x->n--;
      np1 = init();
      np1->l= false;
      x->l= true;
      for (j = 3; j < 6; j++) {
         np3->d[j - 3] = x->d[j];
         np3->child_ptr[j - 3] = x->child_ptr[j];
         np3->n++;
         x->d[j] = 0;
         x->n--;
      }
      for (j = 0; j < 6; j++) {
         x->child_ptr[j] = NULL;
      }
      np1->d[0] = mid;
      np1->child_ptr[np1->n] = x;
      np1->child_ptr[np1->n + 1] = np3;
      np1->n++;
      r = np1;
   } else {
      y = x->child_ptr[i];
      mid = y->d[2];
      y->d[2] = 0;
      y->n--;
      for (j = 3; j <6 ; j++) {
         np3->d[j - 3] = y->d[j];
         np3->n++;
         y->d[j] = 0;
         y->n--;
      }
      x->child_ptr[i + 1] = y;
      x->child_ptr[i + 1] = np3;
   }
   return mid;
}

void insert(int a) {
   int i, t;
   x = r;
   if (x == NULL) {
      r = init();
      x = r;
   } else {
      if (x->l== true && x->n == 6) {
         t = split_child(x, -1);
         x = r;
         for (i = 0; i < (x->n); i++) {
            if ((a >x->d[i]) && (a < x->d[i + 1])) {
               i++;
               break;
            } else if (a < x->d[0]) {
               break;
            } else {
               continue;
            }
         }
         x = x->child_ptr[i];
      } else {
         while (x->l == false) {
            for (i = 0; i < (x->n); i++) {
               if ((a >x->d[i]) && (a < x->d[i + 1])) {
                  i++;
                  break;
               } else if (a < x->d[0]) {
                  break;
               } else {
                  continue;
               }
            }
            if ((x->child_ptr[i])->n == 6) {
               t = split_child(x, i);
               x->d[x->n] = t;
               x->n++;
               continue;
            } else {
               x = x->child_ptr[i];
            }
         }
      }
   }
   x->d[x->n] = a;
   sort(x->d, x->n);
   x->n++;
}

int main() {
   int i, n, t;
   cout<<"enter the no of elements to be inserted\n";
   cin>>n;
   for(i = 0; i < n; i++) {
      cout<<"enter the element\n";
      cin>>t;
      insert(t);
   }
   cout<<"traversal of constructed B tree\n";
   traverse(r);
}