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实施B树的C ++程序

2024-04-20 07:34:04 487

B树是二叉搜索树的概括，一个节点可以有两个以上的子节点。它基本上是一种自平衡树数据结构，用于维护排序的数据，并允许在对数时间顺序访问，搜索，插入和删除。

这是一个实现6阶B树的C++程序。

算法

Begin
   function insert() to insert the nodes into the tree:
      Initialize x as root.
   if x is leaf and having space for one more info then insert a to x.
   else if x is not leaf, do
      Find the child of x that is going to be traversed next.
      If the child is not full, change x to point to the child.
      If the child is full, split it and change x to point to one of the two parts of the child. If a is smaller
      than mid key in the child, then set x as first part of the child. Else second part of the child. When split    the child, move a key from the child to its parent x.
End

范例程式码

#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);
}

输出结果

enter the no of elements to be inserted
7
enter the element
10
enter the element
20
enter the element
30
enter the element
40
enter the element
50
enter the element
60
enter the element
70
traversal of constructed B tree
10 20
30
40 50 60 70

返回顶部
3162201930
czq8825@qq.com

实施B树的C ++程序

算法

范例程式码

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