poj 1804 Brainman

合并排序求逆序对，和poj2299一样，写一下为了再熟悉一下merge sort

#include<iostream>using namespace std;#define N 1005int a[N],b[N];int cnt;void merge(int s[],int d[],int l,int m,int r){int i,j,k,q;i=k=l;j=m+1;while(i<=m&&j<=r){if(s[i]<=s[j])d[k++]=s[i++];else{cnt+=(m-i+1);d[k++]=s[j++];}}if(i>m)for(q=j;q<=r;q++)d[k+q-j]=s[q];elsefor(q=i;q<=m;q++)d[k+q-i]=s[q];for(q=l;q<=r;q++)s[q]=d[q];}void mergesort(int s[],int left,int right){if(left<right){int i=(left+right)/2;mergesort(s,left,i);mergesort(s,i+1,right);merge(s,b,left,i,right);}}int main(){int ca,n,i,j;scanf("%d",&ca);for(j=1;j<=ca;j++){scanf("%d",&n);for(i=1;i<=n;i++)scanf("%d",a+i);cnt=0;mergesort(a,1,n);printf("Scenario #%d:/n",j);printf("%d/n/n",cnt);}return 0;}