/*====================*/ | BTree.h | /*====================*/ #ifndef _BTREE_H_ #define _BTREE_H_ #define NUM 3 #define KeyType int #define Status int typedef struct BTNode { int keynum; struct BTNode * parent; KeyType key[NUM+1]; struct BTNode * ptr[NUM+1]; }BTNode,*BTree; typedef struct { BTNode * pt; int i; int tag; }Result; Result SearchBTree(BTree T, KeyType K); Status InsertBTree(BTree &T, KeyType K, BTree q, int i); Status CreateBTree(BTree &T, int size, int *key); void PrintBTree(BTree T); #endif /*===================*/ | Btree.c | /*===================*/ #include “BTree.h” #include <stdio.h> #include <stdlib.h> #include <assert.h> Result SearchBTree(BTree T,KeyType k) { Result result; BTree p,pre; Status found = false; int i = 1; p = T; pre = NULL; while (p && !found) { for(i=1;i<p->keynum;i++) { if (k <= p->key[i]) break; } if (k == p->key[i]) found = true; else { pre = p; p = p->ptr[i-1]; } } result.i = i-1; if(found) result.pt = p; else result.pt = pre; result.tag = found; return result; } Status InsertBTree(BTree &T,KeyType K, BTree q,int i) { int j, s; KeyType x; BTree ap, temp; bool finished = false; x = K; ap = NULL; while (q && !finished) { for (j = q->keynum; j > i; j –) { q->key[j + 1] = q->key[j]; q->ptr[j + 1] = q->ptr[j]; } q->key[i + 1] = x; q->ptr[i + 1] = ap; q->keynum ++; if (q->keynum < NUM) finished = true; else { s = NUM / 2 + 1; x = q->key[s]; q->keynum = s – 1; ap = (BTree)malloc(sizeof(BTNode)); assert(ap != NULL); ap->keynum = NUM – s; for ( j = 1; j <= NUM – s; j ++) { ap->key[j] = q->key[s + j]; ap->ptr[j – 1] = q->ptr[s + j – 1]; if (ap->ptr[j – 1]!= NULL) ap->ptr[j – 1]->parent = ap; } ap->ptr[NUM – s] = q->ptr[NUM]; if (ap->ptr[NUM – s] != NULL) ap->ptr[j – 1]->parent = ap; q = q->parent; //向上分裂 if (q) //求出i的值 { for (j = 1; j <= q->keynum && x > q->key[j]; j ++) NULL; ap->parent = q; i = j – 1; } }//else }//while if (!finished) //q = NULL; { temp = (BTree)malloc(sizeof(BTNode)); assert(temp != NULL); temp->parent = NULL; temp->keynum = 1; temp->key[1] = x; temp->ptr[0] = T; temp->ptr[1] = ap; if (ap != NULL) ap->parent = temp; if (T != NULL) T->parent = temp; T = temp; } return true; } Status CreateBTree(BTree &T, int size, int *key) { Result result; int i; for (i = 0; i < size; i ++) { result = SearchBTree(T, key[i]); if (!result.tag) //需要插入 if (!InsertBTree(T, key[i],result.pt, result.i)) return false; } return true; } void PrintBTree(BTree T) { int front,rear, i, count; BTree Queue[1000], temp; front = rear = 0; Queue[rear ++] = T; while (front < rear) { temp = Queue[front++]; if (temp != NULL) { count = 0; for (i = 0; i <= temp->keynum; i ++) if (temp->ptr[i] != NULL) count ++; printf(“[%d]”, count); for ( i = 1; i <= temp->keynum; i ++) printf(“%d “, temp->key[i]); printf(“/n”); for (i = 0; i <= temp->keynum; i ++) Queue[rear ++] = temp->ptr[i]; } } } ////////////////////////////////////////////////////////////////////////// int main(void) { BTree T = NULL; int key[15] = { 45, 24, 53, 90, 3, 12, 37, 50, 61, 70, 100, 30, 26, 85, 7}; CreateBTree(T, 15, key); PrintBTree(T); return 1; }