【CFを打って、アルゴリズムを学びます——2つ星】Codeforces Round#312(Div.2)A Lala Land and Apple Trees

3371 ワード

CodeForce プログラミング問題——その他【CFをかけるアルゴリズムを学ぶ

【CF概要】
提出リンク:A.La Land and Apple Trees
問題:
A. Lala Land and Apple Trees
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output
Amr lives in Lala Land. Lala Land is a very beautiful country that is located on a coordinate line. Lala Land is famous with its apple trees growing everywhere.
Lala Land has exactly n apple trees. Tree numberi is located in a position xi and has ai apples growing on it. Amr wants to collect apples from the apple trees. Amr currently stands inx = 0 position. At the beginning, he can choose whether to go right or left. He'll continue in his direction until he meets an apple tree he didn't visit before. He'll take all of its apples and then reverse his direction, continue walking in this direction until he meets another apple tree he didn't visit before and so on. In the other words, Amr reverses his direction when visiting each new apple tree. Amr will stop collecting apples when there are no more trees he didn't visit in the direction he is facing.
What is the maximum number of apples he can collect?
Input
The first line contains one number n (1 ≤ n ≤ 100), the number of apple trees in Lala Land.
The following n lines contains two integers eachxi,ai ( - 105 ≤ xi ≤ 105,xi ≠ 0,1 ≤ ai ≤ 105), representing the position of thei-th tree and number of apples on it.
It's guaranteed that there is at most one apple tree at each coordinate. It's guaranteed that no tree grows in point0.
Output
Output the maximum number of apples Amr can collect.
Sample test(s)
Input

2
-1 5
1 5

Output

Input

Output

Input

Output

Note
In the first sample test it doesn't matter if Amr chose at first to go left or right. In both cases he'll get all the apples.
In the second sample test the optimal solution is to go left to x = - 1, collect apples from there, then the direction will be reversed, Amr has to go tox = 1, collect apples from there, then the direction will be reversed and Amr goes to the final treex = - 2.
In the third sample test the optimal solution is to go right to x = 1, collect apples from there, then the direction will be reversed and Amr will not be able to collect anymore apples because there are no apple trees to his left.
问题:正と負の位置の数が同じならば、すべて取ることができて、もし异なっているならば、そんなに少ない侧は全部取って、多い侧は0に近い(少ない数量+1个)を取ります.
コード:

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include  
#include 
#include 
using namespace std;
struct apple_Tree
{
   int amount,pos;
}store[100010];
bool cmp(apple_Tree a,apple_Tree b)
{
    return a.pos=(n-2*cntzheng-1);j--)
            ans+=store[j].amount;
        }
        cout<

SPOJ 4206二分整合HKアルゴリズム

atoiアルゴリズム