zoukankan      html  css  js  c++  java
  • FZU

    Let’s start with a very classical problem. Given an array a[1…n] of positive numbers, if the value of each element in the array is distinct, how to find the maximum element in this array? You may write down the following pseudo code to solve this problem:

    function find_max(a[1…n])

    max=0;

    for each v from a

    if(max<v)

    max=v;

    return max;

    However, our problem would not be so easy. As we know, the sentence ‘max=v’ would be executed when and only when a larger element is found while we traverse the array. You may easily count the number of execution of the sentence ‘max=v’ for a given array a[1…n].

    Now, this is your task. For all permutations of a[1…n], including a[1…n] itself, please calculate the total number of the execution of the sentence ‘max=v’. For example, for the array [1, 2, 3], all its permutations are [1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 1, 2] and [3, 2, 1]. For the six permutations, the sentence ‘max=v’ needs to be executed 3, 2, 2, 2, 1 and 1 times respectively. So the total number would be 3+2+2+2+1+1=11 times.

    Also, you may need to compute that how many times the sentence ‘max=v’ are expected to be executed when an array a[1…n] is given (Note that all the elements in the array is positive and distinct). When n equals to 3, the number should be 11/6= 1.833333.

    Input

    The first line of the input contains an integer T(T≤100,000), indicating the number of test cases. In each line of the following T lines, there is a single integer n(n≤1,000,000) representing the length of the array.

    Output

    For each test case, print a line containing the test case number (beginning with 1), the total number mod 1,000,000,007

    and the expected number with 6 digits of precision, round half up in a single line.

    Sample Input

    2
    2
    3
    

    Sample Output

    Case 1: 3 1.500000
    Case 2: 11 1.833333

    思路;第n项的交换次数为F[n]=(n-1)!+F[n-1]*n;后面的为res[n]=1.0/n+res[n-1];
    预处理一下输出就行了
    代码:
    #include<cstdio>
    #include<iostream>
    #include<cstring>
    #include<algorithm>
    #include<queue>
    #include<stack>
    #include<set>
    #include<map>
    #include<vector>
    #include<cmath>
    
    const int maxn=1e5+5;
    const int mod=1e9+7;
    typedef long long ll;
    using namespace std;
    ll f[10*maxn];
    double res[10*maxn];
    int main()
    {
        ll a=1;
        f[0]=0;
        f[1]=1;
        res[1]=1;
        for(int t=2;t<=1000000;t++)
        {
            f[t]=((a*(t-1))%mod+((t)*f[t-1])%mod)%mod;
            a=(a*(t-1))%mod;
            res[t]=1.0/t+res[t-1];
            //printf("%.6f
    ",res[t]);
        }
        int T;
        int  n;
        cin>>T;
        int cnt=1;
        while(T--)
        {
          scanf("%d",&n);
          
          printf("Case %d: %d ",cnt++,f[n]);
          printf("%.6f
    ",res[n]);
          
        }
        return 0;
    }



  • 相关阅读:
    python测试开发django-39.xadmin详情页面布局form_layout
    Linux学习20-nohup挂后台启动django
    python测试开发django-38.多对多(ManyToManyField)查询
    python测试开发django-37.外键(ForeignKey)查询
    因子分解机模型简介
    Social regularizations
    MathType插入带序号公式的两种方法
    通俗解释遗传算法及其Matlab实现
    矩阵中路径数目问题
    Word绘制跨行表格
  • 原文地址:https://www.cnblogs.com/Staceyacm/p/10840355.html
Copyright © 2011-2022 走看看