为毛wa了50.。。。

#include<stdio.h>
int solve(long long ,long long );
long long n,i,k,tot1,tot2,tot3,now,l1,l2,ans;
long long w[500010],a[500010],b[500010],c[500010];
int main()
{

    scanf("%d",&n);
    for (i=1;i<=n;i++)
    scanf("%d",&w[i]);
    solve(1,n);
    printf("%d",ans);
    return 0;
} 
int solve(long long x,long long y)
{
    if ((y-x)>1) {solve(x,(x+y)/2);solve((x+y)/2+1,y);}
    if (y==x) return 0;
    tot1=0;tot2=0;
    for (k=x;k<=(x+y)/2;k++)
    { 
    tot1++; 
      a[tot1]=w[k];
}
    for (k=(x+y)/2+1;k<=y;k++)
    {
        tot2++;
        b[tot2]=w[k]; 
    }
    now=0;l1=1;l2=1;
    while ((l1<=tot1)&&(l2<=tot2))
    {
        if (a[l1]<=b[l2]) {now++;c[now]=a[l1];l1++;}
        else {ans+=tot1-l1+1;now++;c[now]=b[l2];l2++;}
    }
    if (l1<=tot1) while (l1<=tot1) {now++;c[now]=a[l1];l1++;}
    if (l2<=tot2) while (l2<=tot2) {now++;c[now]=b[l2];l2++;}
    now=1;
    for (k=x;k<=y;k++)
    {
        w[k]=c[now];
        now++;
    }
    return 0;
}