程序填空题：B+ Tree - Find Key

The function `FindKey` is to check if a given `key` is in a B+ Tree with its root pointed by `root`.

Return `true` if `key` is in the tree, or `false` if not. The B+ tree structure is defined as following:

```
static int order = DEFAULT_ORDER;
typedef struct BpTreeNode BpTreeNode;
struct BpTreeNode {
BpTreeNode** childrens; /* Pointers to childrens. This field is not used by leaf nodes. */
ElementType* keys;
BpTreeNode* parent;
bool isLeaf; /* 1 if this node is a leaf, or 0 if not */
int numKeys; /* This field is used to keep track of the number of valid keys.
In an internal node, the number of valid pointers is always numKeys + 1. */
};


bool FindKey(BpTreeNode * const root, ElementType key){
if (root == NULL) {
return false;
}
int i = 0;
BpTreeNode * node = root;
while () {
i = 0;
while (i < node->numKeys) {
if () i++;
else break;
}
node = node->childrens[i];
}
for(i = 0; i < node->numKeys; i++){
if(node->keys[i] == key)
return true;
}
return false;
}
```






答案：
第1空：!node->isLeaf ||

第2空：key >= node->keys[i] ||