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  • 2013多校联合3 G The Unsolvable Problem(hdu 4627)

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    http://acm.hdu.edu.cn/showproblem.php?pid=4627

    The Unsolvable Problem

    Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
    Total Submission(s): 230    Accepted Submission(s): 136

    Problem Description
    There are many unsolvable problem in the world.It could be about one or about zero.But this time it is about bigger number.
    Given an integer n(2 <= n <= 109).We should find a pair of positive integer a, b so that a + b = n and [a, b] is as large as possible. [a, b] denote the least common multiplier of a, b.
     
    Input
    The first line contains integer T(1<= T<= 10000),denote the number of the test cases.
    For each test cases,the first line contains an integer n.
     
    Output
    For each test cases,print the maximum [a,b] in a line.


    标准签到题,先特判n==2的情况,否则若n为奇数,则答案显然是n/2 和 n/2+1,若n为偶数设n=2*k,若k为偶数,则答案为k-1,k+1,否则答案为k-2,k+2。

      1. #include <iostream>  
      2. #include <string.h>  
      3. #include <stdio.h>  
      4. #include <algorithm>  
      5. #define ll long long  
      6. using namespace std;  
      7. int main()  
      8. {  
      9.     //freopen("dd.txt","r",stdin);  
      10.     ll n,ncase;  
      11.     cin>>ncase;  
      12.     while(ncase--)  
      13.     {  
      14.         cin>>n;  
      15.         if(n==2)  
      16.         cout<<1<<endl;  
      17.         else  
      18.         {  
      19.             if(n%2)  
      20.             cout<<(n/2)*(n-n/2)<<endl;  
      21.             else  
      22.             {  
      23.                 if((n/2)%2==0)  
      24.                 cout<<(n/2-1)*(n/2+1)<<endl;  
      25.                 else  
      26.                 cout<<(n/2-2)*(n/2+2)<<endl;  
      27.             }  
      28.         }  
      29.     }  
      30.     return 0;  
      31. }
      32. 一开始用暴力,唉,挂了,但是为什么是这样呢,想了半天终于明白了。
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  • 原文地址:https://www.cnblogs.com/zhaoxinshanwei/p/3619245.html
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