BZOJ 2212/BZOJ 3702

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxn 400500
using namespace std;
int n,l[maxn],r[maxn],val[maxn],x,roots,root[maxn];
int ls[maxn*20],rs[maxn*20],sum[maxn*20],tot=0,cnt=0;
long long ans=0,cnt1,cnt2;
int read()
{
char ch;int data=0;
while (ch<'0' || ch>'9') ch=getchar();
while (ch>='0' && ch<='9')
{
data=data*10+ch-'0';
ch=getchar();
}
return data;
}
void get_tree(int &now)
{
x=read();
now=++cnt;val[now]=x;
if (x) return;
get_tree(l[now]);
get_tree(r[now]);

}
void pushup(int now)
{
sum[now]=sum[ls[now]]+sum[rs[now]];
}
void build(int &now,int left,int right,int val)
{
now=++tot;
if (left==right) {sum[now]=1;return;}
int mid=(left+right)>>1;
if (val<=mid) build(ls[now],left,mid,val);
else build(rs[now],mid+1,right,val);
pushup(now);return;
}
int merge(int x,int y)
{
if (!x) return y;
if (!y) return x;
cnt1+=(long long)sum[rs[x]]*sum[ls[y]];
cnt2+=(long long)sum[ls[x]]*sum[rs[y]];
ls[x]=merge(ls[x],ls[y]);
rs[x]=merge(rs[x],rs[y]);
pushup(x);
return x;
}
void dfs(int x)
{
if (!x) return;
dfs(l[x]);dfs(r[x]);
if (!val[x])
{
cnt1=cnt2=0;
root[x]=merge(root[l[x]],root[r[x]]);
ans+=min(cnt1,cnt2);
}
return;
}
int main()
{
n=read();
get_tree(roots);
for (int i=1;i<=cnt;i++)
if (val[i]) build(root[i],1,n,val[i]);
dfs(1);
printf("%lld\n",ans);
return 0;
}