解题报告：线段树的查询

/**
* Definition of SegmentTreeNode:
* class SegmentTreeNode {
* public:
*     int start, end, max;
*     SegmentTreeNode *left, *right;
*     SegmentTreeNode(int start, int end, int max) {
*         this->start = start;
*         this->end = end;
*         this->max = max;
*         this->left = this->right = NULL;
*     }
* }
*/
class Solution {
public:
/**
*@param root, start, end: The root of segment tree and
*                         an segment / interval
*@return: The maximum number in the interval [start, end]
*/
int query(SegmentTreeNode *root, int start, int end) {
// write your code here
if (root == nullptr)return 0;
SegmentTreeNode *left = root->left, *right = root->right;
if (end<root->start)return 0;//end超出了最左
if (start>root->end)return 0;//start超出了最右
if (start<root->start)start = left->start;//start超出了最左
if (end>root->end)end = right->end;//end超出了最右
if (start == root->start&&end == root->end)return root->max;
if (left->end >= end){//完全左侧
return query(left, start, end);
}
if (right->start <= start){//完全右侧
return query(right, start, end);
}
return  max(query(left, start, left->end), query(right, right->start, end));//左右之间都有
}
};