左神算法进阶班3_1构造数组的MaxTree

 1 void creatMaxTree(Node*& root, vector<int>v)
 2 {//以下代码都是以数组的下角标为根据
 3     vector<Node*>node;
 4     vector<pair<int, int>>res;//存储每个数的左右大小的数
 5     res.resize(v.size());    
 6     deque<int>d;//单调栈
 7     for (int i = 0; i < v.size(); ++i)
 8     {
 9         Node* p = new Node(v[i]);
10         node.push_back(p);//先生成相关的节点
11         while (!d.empty() && v[i] > v[d.back()])
12         {
13             int index = d.back();
14             d.pop_back();
15             if (d.empty())//有右大值，无左大值
16                 res[index] = pair<int, int>(-1, i);
17             else//有右大值和左大值
18                 res[index] = pair<int, int>(d.back(), i);
19         }
20         d.push_back(i);
21     }
22     while (!d.empty())
23     {
24         int index = d.back();
25         d.pop_back();
26         if (d.empty())//即无右大值，又无左大值
27             res[index] = pair<int, int>(-1, -1);
28         else//无右大值有左大值
29             res[index] = pair<int, int>(d.back(), -1);
30     }
31     for (int i = 0; i < res.size(); ++i)
32     {
33         int a, b;
34         a = res[i].first;
35         b = res[i].second;
36         if (a == -1 && b == -1)//即无右大值，又无左大值为根节点
37             root = node[i];
38         else if (a == -1 && b != -1)
39             node[b]->rchild = node[i];
40         else if (a != -1 && b == -1)
41             node[a]->lchild = node[i];
42         else if (v[a] > v[b])
43             node[b]->rchild = node[i];
44         else
45             node[a]->lchild = node[i];
46     }    
47 }

The shape of tree is:
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                          v5v
                                                            v3v
                                           ^4^
                                                            ^2^
         H6H
                          ^1^
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