实施B树的C ++程序
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