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]