zoukankan      html  css  js  c++  java
  • 2016 Multi-University Training Contest 2 第一题Acperience

    Acperience

    Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)

    Problem Description 
    Deep neural networks (DNN) have shown significant improvements in several application domains including computer vision and speech recognition. In computer vision, a particular type of DNN, known as Convolutional Neural Networks (CNN), have demonstrated state-of-the-art results in object recognition and detection.

    Convolutional neural networks show reliable results on object recognition and detection that are useful in real world applications. Concurrent to the recent progress in recognition, interesting advancements have been happening in virtual reality (VR by Oculus), augmented reality (AR by HoloLens), and smart wearable devices. Putting these two pieces together, we argue that it is the right time to equip smart portable devices with the power of state-of-the-art recognition systems. However, CNN-based recognition systems need large amounts of memory and computational power. While they perform well on expensive, GPU-based machines, they are often unsuitable for smaller devices like cell phones and embedded electronics.

    In order to simplify the networks, Professor Zhang tries to introduce simple, efficient, and accurate approximations to CNNs by binarizing the weights. Professor Zhang needs your help.

    More specifically, you are given a weighted vector W=(w1,w2,…,wn). Professor Zhang would like to find a binary vector B=(b1,b2,…,bn) (bi∈{+1,−1}) and a scaling factor α≥0 in such a manner that ∥W−αB∥2 is minimum.

    Note that ∥⋅∥ denotes the Euclidean norm (i.e. ∥X∥=x21+⋯+x2n‾‾‾‾‾‾‾‾‾‾‾‾√, where X=(x1,x2,…,xn)).

    Input 
    There are multiple test cases. The first line of input contains an integer T, indicating the number of test cases. For each test case:

    The first line contains an integers n (1≤n≤100000) – the length of the vector. The next line contains n integers: w1,w2,…,wn (−10000≤wi≤10000).

    Output 
    For each test case, output the minimum value of ∥W−αB∥2 as an irreducible fraction “p/q” where p, q are integers, q>0.

    Sample Input 
    3 
    4 
    1 2 3 4 
    4 
    2 2 2 2 
    5 
    5 6 2 3 4

    Sample Output 
    5/1 
    0/1 
    10/1 

    题解说的很明白了,但是要注意转换成分数的时候。分数运算的时候需要先约分在进行计算,不然会爆long long,也是刚刚才留意到。。

    #include <cstdio>
    #include <iostream>
    using namespace std;
    #define LL long long
    LL n;
    LL x;
    LL gcd(LL a,LL b)
    {
        return b==0 ? a:gcd(b,a%b);
    }
    int main()
    {
        LL T;
        scanf("%d", &T);
        while(T --)
        {
            scanf("%lld", &n);
            LL b = 0, c = 0;
            for(int i = 0; i < n; i ++)
            {
                scanf("%lld", &x);
                if(x>0) b=b+x;
                else b=b-x;
                c=c+x*x;
            }
            LL a = n * c - b * b;
            LL d = gcd(a, n);
            printf("%lld/%lld
    ",a/d, n/d);
        }
        return 0;
    }
    View Code

     

  • 相关阅读:
    Java核心技术Java程序设计
    Mac下查看 Java 安装目录位置和安装数量
    Intellij IDEA快捷键与使用小技巧
    Java 8 新特性 用 Collectors 对 List 去重
    onInterceptTouchEvent()与onTouchEvent()的机制
    Android 开发之多线程处理、Handler
    安卓中使用XmlPullParser解析xml文件
    监控部署nagios+snmp
    阿里RDS数据库 全量备份恢复到本地MYSQL
    20120412
  • 原文地址:https://www.cnblogs.com/hfc-xx/p/5693030.html
Copyright © 2011-2022 走看看