[决策单调性 分治||单调栈 DP] BZOJ 2739 最远点

决策单调性 用分治或者单调栈 

单调栈没打过 尴尬

#include<cstdio>#include<cstdlib>#include<algorithm>using namespace std;typedef long long ll;inline char nc(){static char buf[100000],*p1=buf,*p2=buf;if (p1==p2) { p2=(p1=buf)+fread(buf,1,100000,stdin); if (p1==p2) return EOF; }return *p1++;}inline void read(int &x){char c=nc(),b=1;for (;!(c>='0' && c<='9');c=nc()) if (c=='-') b=-1;for (x=0;c>='0' && c<='9';x=x*10+c-'0',c=nc()); x*=b;} const int N=1000005;inline ll sqr(ll x){ return x*x; }struct Point{int x,y,idx;void read(int i){::read(x); ::read(y); idx=i;}friend ll dist(Point& A,Point &B){return sqr(A.x-B.x)+sqr(A.y-B.y);}}P[N];int n;int ans[N];bool cmp(int i,int j,int k){    ll x=dist(P[i],P[j]);    ll y=dist(P[i],P[k]);    if(j<i || j>i+n) x=-1LL<<60;    if(k<i || k>i+n) y=-1LL<<60;    return x==y?P[j].idx>P[k].idx:x<y;}inline void Solve(int l,int r,int a,int b){if (l>r) return;int mid=(l+r)>>1,dm=a;for (int i=a+1;i<=b;i++) if(cmp(mid,dm,i)) dm=i;ans[mid]=P[dm].idx;Solve(l,mid-1,a,dm);Solve(mid+1,r,dm,b);} int main(){int Q;freopen("t.in","r",stdin);freopen("t.out","w",stdout);read(Q);while (Q--){read(n); for (int i=1;i<=n;i++) P[i].read(i),P[n+i]=P[i];Solve(1,n,1,n<<1);for (int i=1;i<=n;i++)printf("%d\n",ans[i]);}return 0;}