The Fourth Dimension Space

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Topcoder 463 Div 2 1000

Problem Statement

     Taro and Hanako are playing a game called Nisoku, which is played as follows. Initially, there is a pile of cards. Each card contains a real number between 1.5 and 10.0, inclusive. You are given a vector <double> cards, the i-th element of which is the number written on the i-th card.

Repeat the following step until there is only one card left in the pile: Remove any two cards from the pile, and add one new card to the pile. Write either a+b or a*b on the new card, where a and b are the numbers written on the two cards that were removed.

Return the maximal possible number written on the final card in the pile.

Definition

    
Class: Nisoku
Method: theMax
Parameters: vector <double>
Returns: double
Method signature: double theMax(vector <double> cards)
(be sure your method is public)
    

Notes

- Your return value must have an absolute or relative error less than 1e-9.

Constraints

- cards will contain between 2 and 50 elements, inclusive.
- Each element of cards will be between 1.5 and 10.0, inclusive.

Examples

0)
     
{5, 8}
 
Returns: 40.0
5 * 8 = 40.
1)
     
{1.5, 1.8}
 
Returns: 3.3
1.5 + 1.8 = 3.3.
2)
     
{8.26, 7.54, 3.2567}
 
Returns: 202.82857868
3)
     
{1.5, 1.7, 1.6, 1.5}
 
Returns: 9.920000000000002
4)
     
{10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
                                    10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
                                    10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
                                    10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
                                    10, 10, 10, 10, 10, 10, 10, 10, 10, 10}
 
Returns: 1.0E50
The answer can be extremely big.




发现偶还是太水了。。。

#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;



class Nisoku
{
public:
    double theMax(vector<double>cards)
    {    
        int i,j;
        sort(cards.begin(),cards.end());
        double ans=0;
        for(i=0;i<=cards.size();i+=2)
        {
            double p=1;
            for(j=0;j<i/2;j++)
                p*=(cards[j]+cards[i-1-j]);
            for(j=i;j<cards.size();j++)
                p*=cards[j];
            ans=max(ans,p);
        }
        return ans;
    }
};

谁能证明下这份代码的正确性？

posted on 2010-03-02 22:27 abilitytao 阅读(1052) 评论(0)  编辑 收藏 引用


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