btree_node *btree_delete(btree_node *root, int target)
{
if(1 == root->num)
{
btree_node *y = root->p[0];
btree_node *z = root->p[1];
if(NULL != y && NULL != z &&
M - 1 == y->num && M - 1 == z->num)
{
btree_merge_child(root, 0, y, z);
free(root);
btree_delete_nonone(y, target);
return y;
}
else
{
btree_delete_nonone(root, target);
return root;
}
}
else
{
btree_delete_nonone(root, target);
return root;
}
}
void BPlusTree::btree_delete_nonone(btree_node *root, int target)
{
if(true == root->is_leaf) {
int i = 0;
while(i < root->num && target > root->k[i]) i++;
if(target == root->k[i]) {
for(int j = i + 1; j < 2 * M - 1; j++) {
root->k[j-1] = root->k[j];
}
root->num -= 1;
btree_node_num-=1;
} else {
printf("target not found\n");
}
} else {
int i = 0;
btree_node *y = NULL, *z = NULL;
while(i < root->num && target > root->k[i]) i++;
y = root->p[i];
if(i < root->num) {
z = root->p[i+1];
}
btree_node *p = NULL;
if(i > 0) {
p = root->p[i-1];
}
if(y->num == M - 1) {
if(i > 0 && p->num > M - 1) {
btree_shift_to_right_child(root, i-1, p, y);
} else if(i < root->num && z->num > M - 1) {
btree_shift_to_left_child(root, i, y, z);
} else if(i > 0) {
btree_merge_child(root, i-1, p, y);
y = p;
} else {
btree_merge_child(root, i, y, z);
}
btree_delete_nonone(y, target);
} else {
btree_delete_nonone(y, target);
}
}
}
