線段樹

目錄：

• 1.quick sort 和 merge sort 的比較
• 2.quick sort
• 3.merge sort

1. quick sort 和 merge sort 的區別於聯繫

1). 時間複雜度：都是

構建線段樹：

/**
 * Definition of SegmentTreeNode:
 * class SegmentTreeNode {
 * public:
 *     int start, end;
 *     SegmentTreeNode *left, *right;
 *     SegmentTreeNode(int start, int end) {
 *         this->start = start, this->end = end;
 *         this->left = this->right = NULL;
 *     }
 * }
 */


class Solution {
public:
    /*
     * @param start: start value.
     * @param end: end value.
     * @return: The root of Segment Tree.
     */
    SegmentTreeNode * build(int start, int end) {
        // write your code here
        if(start > end){
            return NULL;
        }

        SegmentTreeNode *root = new SegmentTreeNode(start,end);
        if(start==end){
            return root;
        }

        int mid = (start+end)/2;
        root->left = build(start,mid);
        root->right = build(mid+1,end);

        return root;
    }
};

/**
 * Definition of SegmentTreeNode:
 * class SegmentTreeNode {
 * public:
 *     int start, end， max; //min
 *     SegmentTreeNode *left, *right;
 *     SegmentTreeNode(int start, int end, int max) {
 *         this->start = start, this->end = end;
 *         this->left = this->right = NULL;
 *         this->max = max;
 *     }
 * }
 */


class Solution {
public:
    /*
     * @param start: start value.
     * @param end: end value.
     * @return: The root of Segment Tree.
     */
    SegmentTreeNode * buildhelper(int start, int end, int max) {
        // write your code here
        if(start > end){
            return NULL;
        }

        SegmentTreeNode *root = new SegmentTreeNode(start,end,max);
        if(start==end){
            return root;
        }

        int mid = (start+end)/2;
        root->left = build(start,mid);
        root->right = build(mid+1,end);
        root->max = max(root->left->max, root->right->max);

        return root;
    }
};