bzoj4991: [Usaco2017 Feb]Why Did the Cow Cross the Road III

题意

给你两个序列
然后值相同的就连一条边。。
然后如果两条边有相交并且他们的差的绝对值值>k
那么ans++

题解

CDQ分治就好了。。
感觉没太多好说的

#include<cstdio>#include<cstdlib>#include<algorithm>#include<iostream>#include<cstring>typedef long long LL;using namespace std;const int N=110005;int n,k;int X[N],Y[N];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*10+ch-'0';ch=getchar();}    return x*f;}//具体思路：就是x要比他小    y要比他大LL ans=0; struct qq{    int x,y;    bool tf;//询问:true   插入 :false}s[N*2];int num;//一些询问void init (){    n=read();k=read();    for (int u=1;u<=n;u++) X[read()]=u;    for (int u=1;u<=n;u++) Y[read()]=u;}bool cmp (qq a,qq b){return a.x<b.x;}//就按x排序就好了//目标    左边的x大，但y小 int f[N];int lb (int x){return x&(-x);}void add (int x,int y){    while (x<=n)    {        f[x]+=y;        x+=lb(x);    }}int get (int x){    int lalal=0;    while (x>=1)    {        lalal=lalal+f[x];        x-=lb(x);    }    return lalal;}int sta[N],cnt;void dfs (int l,int r){    if (l>=r) return ;    int mid=(l+r)>>1;    dfs(l,mid);dfs(mid+1,r);    sort(s+l,s+mid+1,cmp);sort(s+mid+1,s+1+r,cmp);    int now=l;    int shen=0,cnt=0;    for (int u=mid+1;u<=r;u++)    {        while (now<=mid&&s[now].x<=s[u].x)         {            if (s[now].tf==false) {shen++;add(s[now].y,1);sta[++cnt]=s[now].y;}            now++;        }        if (s[u].tf==true) ans=ans+shen-get(s[u].y-1);    }    for (int u=1;u<=cnt;u++) add(sta[u],-1);    now=mid;    shen=0,cnt=0;    for (int u=r;u>mid;u--)    {        while (now>=l&&s[now].x>=s[u].x)        {            if (s[now].tf==false) {shen++;add(s[now].y,1);sta[++cnt]=s[now].y;}            now--;        }        if (s[u].tf==true) ans=ans+get(s[u].y-1);    }    for (int u=1;u<=cnt;u++) add(sta[u],-1);    return ;}void solve (){    for (int u=1;u<=n;u++)        if (u+k+1<=n)//如果后面也没有询问，那么就没有意义了        {            s[++num].x=X[u];s[num].y=Y[u];s[num].tf=false;            s[++num].x=X[u+k+1];s[num].y=Y[u+k+1];s[num].tf=true;        }    dfs(1,num);}int main(){    init();    solve();    printf("%lld\n",ans);    return 0;}