poj1804

简单题

View Code

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

#define maxn 1006

int n;
int a[maxn], cnt, c[maxn];

void input()
{
scanf("%d", &n);
for (int i = 0; i < n; i++)
scanf("%d", &a[i]);
}

void MergeSort(int l, int r)
{
int mid, i, j, tmp;
if (r > l + 1)
{
mid = (l + r) / 2;
MergeSort(l, mid);
MergeSort(mid, r);
tmp = l;
for ( i = l, j = mid; i < mid && j < r; )
{
if (a[i] > a[j])
{
c[tmp++] = a[j++];
cnt += mid - i;
}
else
c[tmp++] = a[i++];
}
if (j < r)
for (; j < r; ++j)
c[tmp++] = a[j];
else
for(; i < mid; ++i)
c[tmp++] = a[i];
for (i = l; i < r; ++i)
a[i] = c[i];
}
}

int main()
{
//freopen("t.txt", "r", stdin);
int t;
scanf("%d", &t);
for (int i = 0; i < t; i++)
{
input();
cnt = 0;
MergeSort(0, n);
printf("Scenario #%d:\n%d\n\n", i + 1, cnt);
}
return 0;
}