bzoj4409&&bzoj4410&&bzoj4411[Usaco2016 Feb Platinum]题解

辣鸡wyz最近状态奇差，于是想用usaco题找找手感，万万没想到被虐了一脸TAT

先贴代码，有空再填坑

4409[Usaco2016 Feb]Circular barn

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#define ll long long
#define N 2333
 
using namespace std;
inline int read(){
	int ret=0;char ch=getchar();
	while (ch<'0'||ch>'9') ch=getchar();
	while ('0'<=ch&&ch<='9'){
		ret=ret*10-48+ch;
		ch=getchar();
	}
	return ret;
}
 
ll s[N][N];
int n,m,a[N];
ll dp[10][N];
int p[10][N];
int sl[N],sr[N],stk[N],top;
 
int main(){
	n=read();m=read();
	for (int i=1;i<=n;++i) a[i+n]=a[i]=read();
	for (int i=1;i<=n;++i){
		s[n+i][0]=s[i][0]=0;
		for (int j=1;j<=n;++j)
			s[n+i][j]=s[i][j]=s[i][j-1]+(ll)a[i+j-1]*(j-1);
	}
	top=1;sl[0]=0;sr[0]=n+1;
	for (int i=0;i<top;++i){
		stk[i]=(sl[i]+sr[i])/2;
		if (sl[i]+1<stk[i]){
			sl[top]=sl[i];
			sr[top]=stk[i];
			++top;
		}
		if (stk[i]+1<sr[i]){
			sl[top]=stk[i];
			sr[top]=sr[i];
			++top;
		}
	}
 
	ll ans=(1LL<<60);
	for (int st=1;st<=n;++st){
		for (int i=0;i<=n;++i) dp[1][i]=s[st][i],p[1][i]=0;
		for (int k=2;k<=m;++k) p[k][n+1]=n,p[k][0]=0,dp[k][0]=0;
		for (int k=2;k<=m;++k)
			for (int i=0;i<top;++i){
				int now=stk[i];
				dp[k][now]=(1LL<<60);
				for (int j=p[k][sl[i]];j<=p[k][sr[i]]&&j<=now;++j)
					if (dp[k][now]>dp[k-1][j]+s[st+j][now-j]){
						dp[k][now]=dp[k-1][j]+s[st+j][now-j];
						p[k][now]=j;
					}
			}
		ans=min(ans,dp[m][n]);
	}
	printf("%lld\n",ans);
	return 0;
}

4410[Usaco2016 Feb]Fence in

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#define ll long long
#define N 25003
 
using namespace std;
inline int read(){
	int ret=0;char ch=getchar();
	while (ch<'0'||ch>'9') ch=getchar();
	while ('0'<=ch&&ch<='9'){
		ret=ret*10-48+ch;
		ch=getchar();
	}
	return ret;
}
 
int n,m,a[N],b[N];
 
int main(){
	a[0]=read();b[0]=read();n=read();m=read();
	for (int i=n;i;--i) a[i]=read();
	sort(a,a+n+1,greater<int>());
	for (int i=0;i<=n;++i) a[i]=a[i]-a[i+1];
	sort(a,a+n+1);
	for (int i=m;i;--i) b[i]=read();
	sort(b,b+m+1,greater<int>());
	for (int i=0;i<=m;++i) b[i]=b[i]-b[i+1];
	sort(b,b+m+1);
 
	int p=1,q=1;
	ll ans=(ll)a[0]*m+(ll)b[0]*n;
	while (p<=n&&q<=m)
		if (a[p]<b[q])
			ans+=(ll)a[p++]*(m-q+1);
		else
			ans+=(ll)b[q++]*(n-p+1);
	printf("%lld\n",ans);
	return 0;
}

4411[Usaco2016 Feb]Load balancing

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#define N 100005
 
using namespace std;
inline int read(){
	int ret=0;char ch=getchar();
	while (ch<'0'||ch>'9') ch=getchar();
	while ('0'<=ch&&ch<='9'){
		ret=ret*10-48+ch;
		ch=getchar();
	}
	return ret;
}
 
int n;
int c[2][40*N];
 
void modify(int id,int pos,int delta){
	for (int x=1,l=1,r=1e6;;){
		c[id][x]+=delta;
		if (l==r) break;
		int mid=(l+r)/2;
		if (pos<=mid) x=(x<<1),r=mid;
		else x=(x<<1^1),l=mid+1;
	}
}
 
int query(){
	int ds[2]={0,0},us[2]={0,0};
	for (int x=1,l=1,r=1e6;;){
		int ls=x<<1,rs=x<<1^1,mid=(l+r)/2;
		if (l==r) ls=rs=x;
		if (max(ds[0]+c[0][ls],ds[1]+c[1][ls])<max(us[0]+c[0][rs],us[1]+c[1][rs])){
			ds[0]+=c[0][ls];ds[1]+=c[1][ls];x=rs;l=mid+1;
		}
		else{
			us[0]+=c[0][rs];us[1]+=c[1][rs];x=ls;r=mid;
		}
		if (ls==rs) return max(max(ds[0],ds[1]),max(us[0],us[1]));
	}
}
 
struct point{
	int x,y;
} a[N];
inline bool operator <(const point &u,const point &v){
	return u.x<v.x;
}
 
int main(){
	n=read();
	memset(c,0,sizeof(c));
	for (int i=1;i<=n;modify(1,a[i++].y=read(),1)) a[i].x=read();
	sort(a+1,a+n+1);
	int ans=query();
	for (int i=1;i<=n;++i){
		modify(0,a[i].y,1);
		modify(1,a[i].y,-1);
		if (i<n&&a[i].x==a[i+1].x) continue;
		ans=min(ans,query());
	}
	printf("%d\n",ans);
	return 0;
}