60分代码：

#include <bits/stdc++.h> 
using namespace std;
int a[100005];
int main()
{
    int n;scanf("%d", &n);
    for(int i=1;i<=n;i++)scanf("%d", &a[i]);
    int ans=0;
    for(int i=2;i<=n;i++)
    {
        for(int j=i-1;j>=1;j--)
        {
            if(a[j]>a[j+1])
            {
                ans++;
                swap(a[j], a[j+1]);
            }
            else break;
        }
    }
    printf("%d\n", ans);
    return 0;
}

100分代码：

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int a[110005], tmp[110005];
ll ans;
void msort(int l, int r)
{
    if(l >= r)return ;
    int mid=(l + r)/2;
    msort(l, mid);msort(mid+1, r);
    int len = l;
    int i = l, j = mid + 1;
    while(i <= mid && j <= r)
    {
        if(a[i] > a[j])
        {
            ans += mid - i + 1;
            tmp[len++] = a[j++];
        }
        else tmp[len++] = a[i++];
    }
    while(i <= mid)tmp[len++] = a[i++];
    while(j <= r)tmp[len++] = a[j++];
    memcpy(a + l, tmp + l, (r - l + 1)*4);
}
int main()
{
    int n;scanf("%d", &n);
    for(int i=1;i<=n;i++)scanf("%d", &a[i]);
    ans=0;msort(1, n);
    printf("%lld\n", ans);
    return 0;
}