标签：uva   刘汝佳   小白   

Dropping Balls

A number of K balls are dropped one by one from the root of a fully binary tree structure FBT. Each time the ball being dropped first visits a non-terminal node. It then keeps moving down, either follows the path of the left subtree, or follows the path of the right subtree, until it stops at one of the leaf nodes of FBT. To determine a ball‘s moving direction a flag is set up in every non-terminal node with two values, either false or true. Initially, all of the flags are false. When visiting a non-terminal node if the flag‘s current value at this node isfalse, then the ball will first switch this flag‘s value, i.e., from the false to the true, and then follow the left subtree of this node to keep moving down. Otherwise, it will also switch this flag‘s value, i.e., from the true to the false, but will follow the right subtree of this node to keep moving down. Furthermore, all nodes of FBT are sequentially numbered, starting at 1 with nodes on depth 1, and then those on depth 2, and so on. Nodes on any depth are numbered from left to right.

For example, Fig. 1 represents a fully binary tree of maximum depth 4 with the node numbers 1, 2, 3, ..., 15. Since all of the flags are initially set to be false, the first ball being dropped will switch flag‘s values at node 1, node 2, and node 4 before it finally stops at position 8. The second ball being dropped will switch flag‘s values at node 1, node 3, and node 6, and stop at position 12. Obviously, the third ball being dropped will switch flag‘s values at node 1, node 2, and node 5 before it stops at position 10.

Fig. 1: An example of FBT with the maximum depth 4 and sequential node numbers.

Now consider a number of test cases where two values will be given for each test. The first value is D, the maximum depth of FBT, and the second one is I, the I^th ball being dropped. You may assume the value of I will not exceed the total number of leaf nodes for the given FBT.

Please write a program to determine the stop position P for each test case.

For each test cases the range of two parameters D and I is as below: 

Input 

Line 1 		 I the number of test cases 
Line 2 		 
test case #1, two decimal numbers that are separatedby one blank 
... 		 		 
Line k+1 
test case #k 
Line l+1 
test case #l 
Line l+2 -1 		 a constant -1 representing the end of the input file

Output 

Line 1 		 the stop position P for the test case #1 
... 		 
Line k the stop position P for the test case #k 
... 		 
Line l the stop position P for the test case #l

Sample Input 

5
4 2
3 4
10 1
2 2
8 128
-1

Sample Output 

12
7
512
3
255

题意  i个小球在一棵二叉树上下落  第奇数个到达某个节点就往左  否则往右   求最后一个小球下落到最底层所在结点的序号

对于第i个小球  在根结点处  若i是奇数  则它是往左的第(i+1)/2个小球  若i是偶数  则它是往右的第n/2个小球   

而对于一个结点k  它的左子结点序号为2*k   右子节点序号为2*k+1   每次更新i到到最底层就得出结果了

#include<cstdio>
int main()
{
    int cas, ans, d, i;
    while (scanf ("%d", &cas), cas + 1)
    {
        while (cas--)
        {
            ans = 1;
            scanf ("%d%d", &d, &i);
            while (--d)
            {
                if (i % 2)
                    ans = ans * 2, i = (i + 1) / 2;
                else
                    ans = ans * 2 + 1, i = i / 2;
            }
            printf ("%d\n", ans);
        }
    }
    return 0;
}

UVa 679 Dropping Balls,布布扣,bubuko.com

UVa 679 Dropping Balls

标签：uva   刘汝佳   小白   

原文地址：http://blog.csdn.net/iooden/article/details/38400861