First, it's easy to know b b b sequence in a a The order in a must be sorted from small to large, otherwise exchange b b b in reverse order will be better.
Then there is a very ghost conclusion.
set up p i p_i pi indicates that only b i b_i bi} insert a a In a sequence, the optimal position is inserted in a p i − 1 a_{p_i-1} api − 1 − and a p i a_{p_i} api , note that for the same i i i, p i p_i pi # there may be more than one.
Conclusion: if b j < b i b_j<b_i bj < Bi, for multiple p j p_j Any one of pj , exists p i p_i pi makes p j ≤ p i p_j\leq p_i pj≤pi.
prove:
First consider how to obtain the "optimal position" b j b_j bj, let's put a a Less than in a b j b_j The number of bj + 0 0 0, greater than b j b_j The number of bj + 1 1 1, then insert b j b_j bj} position at p j p_j pj's contribution is a 1 , ⋯ , a p j − 1 a_1,\cdots,a_{p_j-1} a1,..., apj − 1 1 1 Number of 1 plus a p j , ⋯ , a n a_{p_j},\cdots,a_n apj,..., an 0 0 Number of 0.
Here, in order to prove the intuition, we do not consider it a a There are and in a b j b_j In the case of bj ^ equal numbers, the proof method considering this case is the same.
Consider the counter evidence method and assume p i < p j p_i<p_j pi < PJ, put the sequence a a a divided into three sections: A = [ 1 , p i − 1 ] A=[1,p_i-1] A=[1,pi−1], B = [ p i , p j − 1 ] B=[p_i,p_j-1] B=[pi,pj−1], C = [ p j , n ] C=[p_j,n] C=[pj,n].
Note from b j b_j bj becomes b i b_i After the test, a a a in the sequence, only 1 1 1 becomes 0 0 0.
set up A 0 , A 1 A_0,A_1 A0, A1 indicates A A Original in A 0 , 1 0,1 Number of 0,1, A 0 ′ , A 1 ′ A'_0,A'_1 A0 ', A1' indicates from b j b_j bj becomes b i b_i bi # rear A A A medium 0 , 1 0,1 Number of 0,1. B , C B,C B. C similarly defined.
that p j p_j pj's contribution is: A 1 + B 1 + C 0 A_1+B_1+C_0 A1+B1+C0.
because p j p_j pj# yes b j b_j The optimal position of bj , so we can put p j p_j pj becomes p i p_i pi , will not be in a better position, so: ( A 1 + B 1 + C 0 ) − ( A 1 + B 0 + C 0 ) ≤ 0 (A_1+B_1+C_0)-(A_1+B_0+C_0)\leq 0 (A1 + B1 + C0) − (A1 + B0 + C0) ≤ 0, i.e B 1 − B 0 ≤ 0 B_1-B_0\leq 0 B1−B0≤0.
p i p_i pi's contribution is: A 1 ′ + B 0 ′ + C 0 ′ A_1'+B_0'+C_0' A1′+B0′+C0′.
Ruoba p i p_i pi , adjust to p j p_j pj# location, contribution: A 1 ′ + B 1 ′ + C 0 ′ A_1'+B_1'+C_0' A1 ′ + B1 ′ + C0 ′ is obtained by subtracting the contribution before adjustment ( A 1 ′ + B 1 ′ + C 0 ′ ) − ( A 1 ′ + B 0 ′ + C 0 ′ ) = B 1 ′ − B 0 ′ (A_1'+B_1'+C_0')-(A_1'+B_0'+C_0')=B_1'-B_0' (A1 ′ + B1 ′ + C0 ′) − (A1 ′ + B0 ′ + C0 ′) = B1 ′− B0 ′, and B 1 ′ − B 0 ′ ≤ B 1 − B 0 ≤ 0 B_1'-B_0'\leq B_1-B_0\leq 0 B1 ′− B0 ′≤ B1 − B0 ≤ 0, so p i p_i pi , adjust to p j p_j pj# must be in a good position, so it must exist p i ≥ p j p_i\geq p_j pi≥pj.
Then we can for each b i b_i bi# plug it directly into the p i p_i According to this conclusion, such interpolation must also meet the requirements b i b_i bi# sorted from small to large.
More precisely, this interpolation first ensures b b b and a a The reverse order pairs between a are the least, and it can be seen from the conclusion that at this time b b b and b b The reverse order pair between b is 0 0 0, also takes the lower bound, and a a a and a a The reverse order pair between a is fixed.
The question now is how to find each value quickly b i b_i The optimal position of bi ^ and its reverse order contribution to.
Using segment tree maintenance [ 1 , i − 1 ] [1,i-1] In [1,i − 1] 1 1 Number of 1+ [ i , n ] [i,n] In [i,n] 0 0 The minimum number of 0.
#include<bits/stdc++.h> #define N 1000010 #define ll long long #define fi first #define se second #define pii pair<int,int> #define mk(a,b) make_pair(a,b) using namespace std; inline int read() { int x=0,f=1; char ch=getchar(); while(ch<'0'||ch>'9') { if(ch=='-') f=-1; ch=getchar(); } while(ch>='0'&&ch<='9') { x=(x<<1)+(x<<3)+(ch^'0'); ch=getchar(); } return x*f; } int T,n,m,nn,a[N],b[N],bb[N<<1]; namespace AA { int c[N<<1],lowbit[N<<1]; void init() { const int t=2000000; for(int i=1;i<=t;i++) lowbit[i]=(i&-i); } void add(int x,int y) { for(;x<=nn;x+=lowbit[x]) c[x]+=y; } int query(int x) { int ans=0; for(;x;x-=lowbit[x]) ans+=c[x]; return ans; } ll work() { for(int i=1;i<=nn;i++) c[i]=0; ll ans=0; for(int i=n;i>=1;i--) { ans+=query(a[i]-1); add(a[i],1); } return ans; } } namespace BA { int minn[N<<2],lazy[N<<2]; void downn(int k,int v) { minn[k]+=v,lazy[k]+=v; } void down(int k) { if(lazy[k]) { downn(k<<1,lazy[k]); downn(k<<1|1,lazy[k]); lazy[k]=0; } } void up(int k) { minn[k]=min(minn[k<<1],minn[k<<1|1]); } void build(int k,int l,int r) { lazy[k]=0; if(l==r) { minn[k]=l-1; return; } int mid=(l+r)>>1; build(k<<1,l,mid); build(k<<1|1,mid+1,r); up(k); } void update(int k,int l,int r,int ql,int qr,int v) { if(ql<=l&&r<=qr) { downn(k,v); return; } down(k); int mid=(l+r)>>1; if(ql<=mid) update(k<<1,l,mid,ql,qr,v); if(qr>mid) update(k<<1|1,mid+1,r,ql,qr,v); up(k); } pii p[N]; ll work() { for(int i=1;i<=n;i++) p[i]=mk(a[i],i); sort(p+1,p+n+1); sort(b+1,b+m+1); build(1,1,n+1); ll ans=0; int tmp1=1,tmp2=1; for(int i=1;i<=m;i++) { while(tmp2<=n&&p[tmp2].fi<=b[i]) { update(1,1,n+1,p[tmp2].se+1,n+1,-1); tmp2++; } while(tmp1<=n&&p[tmp1].fi<b[i]) { update(1,1,n+1,1,p[tmp1].se,1); tmp1++; } ans+=minn[1]; } return ans; } } int main() { AA::init(); T=read(); while(T--) { n=read(),m=read(); for(int i=1;i<=n;i++) bb[i]=a[i]=read(); for(int i=1;i<=m;i++) bb[n+i]=b[i]=read(); sort(bb+1,bb+n+m+1); nn=unique(bb+1,bb+n+m+1)-bb-1; for(int i=1;i<=n;i++) a[i]=lower_bound(bb+1,bb+nn+1,a[i])-bb; for(int i=1;i<=m;i++) b[i]=lower_bound(bb+1,bb+nn+1,b[i])-bb; printf("%lld\n",AA::work()+BA::work()); } return 0; }