acm-杭电-5645

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直接遍历，找出所有ai<aj的对数，再除以n*(n-1）

 Online JudgeOnline ExerciseOnline TeachingOnline ContestsExercise AuthorF.A.QHand In HandOnline AcmersForum | DiscussStatistical ChartsProblem ArchiveRealtime Judge StatusAuthors Ranklist Search     C/C++/Java Exams     ACM StepsGo to JobContest LiveCastICPC@ChinaBest Coder betaVIP | STD ContestsVirtual Contests     DIY | Web-DIY betaRecent ContestsAuthor adolph_junMail Mail 0(0)Control Panel Control Panel Sign Out Sign OutNew~~招聘——壹晨仟阳(杭州)，巴卡斯（杭州），英雄互娱（杭州） 2016 阿里云 红包券 大放送~~View CodeProblem : 5645 ( DZY Loves Balls )     Judge Status : AcceptedRunId : 16633841    Language : C    Author : adolph_junCode Render Status : Rendered By HDOJ C Code Render Version 0.01 Beta#include <stdio.h>int main(){       int t;       int i,j;       float n,m;       int num[500];       scanf ("%d",&t);       while (t--)       {              m=0;              memset(num,0,sizeof(num));              scanf ("%f",&n);              for (i=0; i<n; i++)              {                     scanf ("%d",&num[i]);              }              for (i=0; i<n; i++)              {                     for (j=0; j<n; j++)                     {                            if(num[i]>num[j]) m++;                     }              }              //printf("%f  %f",n,m);              printf("%f\n",m/(n*(n-1.0)));       }       return 0;}

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