HDU 5323 SOLVE THIS INTERESTING PROBLEM爆捜

リンク
Solve this interesting problem
Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 511    Accepted Submission(s): 114
Problem Description
Have you learned something about segment tree? If not, don’t worry, I will explain it for you.
Segment Tree is a kind of binary tree, it can be defined as this:
- For each node u in Segment Tree, u has two values: 
Lu  and 
Ru .
- If 
Lu=Ru , u is a leaf node. 
- If 
Lu≠Ru , u has two children x and y,with 
Lx=Lu ,
Rx=⌊Lu+Ru2⌋ ,
Ly=⌊Lu+Ru2⌋+1 ,
Ry=Ru .
Here is an example of segment tree to do range query of sum.
Given two integers L and R, Your task is to find the minimum non-negative n satisfy that: A Segment Tree with root node's value 
Lroot=0  and 
Rroot=n contains a node u with 
Lu=L  and 
Ru=R .
 
Input
The input consists of several test cases. 
Each test case contains two integers L and R, as described above.
0≤L≤R≤109
LR−L+1≤2015
 
Output
For each test, output one line contains one integer. If there is no such n, just output -1.
 
Sample Input

   
   
   
   

    
    
    
    6 7
10 13
10 11
   
   
   
   

 
Sample Output

   
   
   
   

    
    
    
    7
-1
12
   
   
   
   

 
Source
2015 Multi-University Training Contest 3
 
タイトル:
所与の区間[l,r]
セグメントツリーの再帰ツリー方式build(1,n)
最小のnがどれだけあるかを聞いて、build(1,n)の中で直接区間を建てることができるようにします[l,r]
考え方:
範囲に注意して推計すると,この領域の間隔はルートノードから10を超えないことが分かった.
だから底から上を探せばいい
コード#コード#