NOIP2017 Day2 小结

Posted 2020-10-14 Stump

T1

并查集维护联通图

预计得分100

#include<stdio.h>
#include<iostream>
#include<cmath>
#define FOR(i,s,t) for(register int i=s;i<=t;++i)
using namespace std;
typedef long long ll;
typedef double db;
const int BIG=2333;
int f[BIG]; 
int n,T;
int s1[BIG],s2[BIG];
struct node{
	ll x,y,z;
}p[BIG];
ll h,r;
int fi,fj;
inline int find(int x){
	return f[x]==x?x:f[x]=find(f[x]);
}
inline ll dis(int i,int j){
	return -1ll*r*r+1ll*(p[i].x-p[j].x)*(p[i].x-p[j].x)-1ll*r*r+1ll*(p[i].y-p[j].y)*(p[i].y-p[j].y)-1ll*r*r+1ll*(p[i].z-p[j].z)*(p[i].z-p[j].z)-1ll*r*r;
}
int main(){
	scanf("%d",&T);
	die:;
	while(T--){
		scanf("%d%lld%lld",&n,&h,&r);
		FOR(i,1,n)f[i]=i,s1[i]=s2[i]=0;
		FOR(i,1,n)scanf("%lld%lld%lld",&p[i].x,&p[i].y,&p[i].z);
		FOR(i,1,n)
			FOR(j,i+1,n){
				if(dis(i,j)<=0){
					fi=find(i);
					fj=find(j);
					if(fi!=fj)f[fi]=fj;
				}
			}
		FOR(i,1,n){
			if(p[i].z-r<=0&&p[i].z+r>=0)
				s1[find(i)]=1;
			if(p[i].z-r<=h&&p[i].z+r>=h)
				s2[find(i)]=1;
		}
		FOR(i,1,n)
			if(s1[i]==1&&s2[i]==1){
				puts("Yes");
				goto die;
			}
		puts("No");
	}
	return 0;
}

T2

搜索+最优性剪枝

luogu上水过90

那就预计得分90

#include<stdio.h>
#include<iostream>
#include<queue>
#include<algorithm>
#define FOR(i,s,t) for(register int i=s;i<=t;++i)
using namespace std;
int ans;
int dis[25][25];
int f[25];
int nxt[2333],las[25],to[2333],dep[25];
int w[2333];
int n,m,M;
int z;
int x,y,cnt,num,tot;
struct edge{
	int l;
	int r;
	int v;
	inline bool operator<(edge A)const{
		return v<A.v;
	}
}e[2333];
const int inf=(1<<28);
int p[2333];
inline void add(int x,int y,int z){
	nxt[++tot]=las[x];
	las[x]=tot;
	to[tot]=y;
	w[tot]=z;
}
inline int find(int x){
	return f[x]==x?x:find(f[x]);
}
queue<int>q;
inline void bfs(int s){
	int sum=0;
	while(!q.empty())q.pop();
	FOR(i,1,n)dep[i]=0;
	dep[s]=1;
	int now;
	q.push(s);
	while(!q.empty()){
		now=q.front();
		q.pop();
		for(register int e=las[now];e;e=nxt[e])
			if(!dep[to[e]]){
				dep[to[e]]=dep[now]+1;
				q.push(to[e]);
				sum=sum+1ll*w[e]*dep[now];
			}
	}
	ans=min(ans,sum);
}
inline void calc(){
	tot=0;
	for(register int i=1;i<=n;++i)
		las[i]=0;
	for(register int i=1;i<n;++i){
		add(e[p[i]].l,e[p[i]].r,e[p[i]].v);
		add(e[p[i]].r,e[p[i]].l,e[p[i]].v);
	}
	FOR(i,1,n)bfs(i);
}
inline void dfs(int t,int st,int sum){
	if(sum>=ans)
		return;
	if(t==n){	
		calc();
		return;
	}
	int l,r;
	for(register int i=st;i<=cnt;++i){
		l=find(e[i].l);
		r=find(e[i].r);
		if(l!=r){
			p[t]=i;
			f[l]=r;
			dfs(t+1,i+1,sum+e[i].v);
			f[l]=l;
		}
	}
}
inline int read(){
	char c;while(c=getchar(),c==‘ ‘||c==‘\n‘);int data=c-48;
	while(c=getchar(),c>=‘0‘&&c<=‘9‘)data=(data<<1)+(data<<3)+c-48;return data;
}
int main(){
	n=read();m=read();
	FOR(i,1,n)FOR(j,1,n)dis[i][j]=inf;
	FOR(i,1,n)dis[i][i]=0;
	FOR(i,1,n)f[i]=i;
	FOR(i,1,m){
		x=read();y=read();z=read();
		dis[x][y]=min(dis[x][y],z);
		dis[y][x]=min(dis[y][x],z);
	}
	FOR(i,1,n)FOR(j,i+1,n)if(dis[i][j]!=inf)e[++cnt]=(edge){i,j,dis[i][j]};
	sort(e+1,e+cnt+1);
	ans=inf;
	dfs(1,1,0);
	printf("%d\n",ans);
	return 0;
}

　　

T3

30分暴力+10分块状链表

好像块状链表写挂了

预计得分30

#include<stdio.h>
#include<iostream>
#include<math.h>
#define FOR(i,s,t) for(register int i=s;i<=t;++i)
using namespace std;
int nxt[200005],af[200005],sz[2001],to[200005],be[2001];
const int big=1001;
int a[5001][5001];
int blo,cnt;
int n,m,t,num,x,y;
inline int read(){
	char c;while(c=getchar(),c==‘ ‘||c==‘\n‘);int data=c-48;
	while(c=getchar(),c>=‘0‘&&c<=‘9‘)data=(data<<1)+(data<<3)+c-48;return data;
}
inline void solve1(){
	blo=sqrt(m);
	FOR(i,1,m){
		if(i%blo==1)be[(i-1)/blo+1]=i;
		nxt[i]=i-1;
		++sz[(i-1)/blo+1];
		to[i]=i;
		af[i]=i+1;
	}
	register int i,j;
	cnt=m;
	while(t--){
		x=read();y=read();
		for(i=1;i<=blo<<1|1;++i)
			if(y>sz[i])y-=sz[i];
			else break;
		for(j=be[i];;){
			--y;
			if(!y)break;
			j=af[j];
		}
		printf("%d\n",to[j]);
		++cnt;
		if(cnt%blo==1)be[(cnt-1)/blo+1]=cnt;
		nxt[cnt]=cnt-1;
		++sz[(cnt-1)/blo+1];
		to[cnt]=to[j];
		af[cnt]=cnt+1;
		nxt[af[j]]=nxt[j];
		af[nxt[j]]=af[j];
		--sz[(j-1)/blo+1];
		if(j%blo==1)
			be[(j-1)/blo+1]=af[j];
	}
	return;
}
inline void solve2(){
	FOR(i,1,n)FOR(j,1,m)a[i][j]=(i-1)*m+j;
		while(t--){
			x=read();y=read();
			num=a[x][y];
			a[x][y]=0;
			FOR(i,y,m)a[x][i]=a[x][i+1];
			FOR(i,x,n)a[i][m]=a[i+1][m];
			a[n][m]=num;
			printf("%d\n",num);
		}
}
int main(){
	n=read();m=read();t=read();
	if(n<=1000&&m<=1000){
		solve2();
		return 0;
	}
	if(n==1){
		solve1();
		return 0;
	}
	solve2();
	return 0;
}

　　

Day2得分100+90+30=220

NOIP2017总得分 100+50+30+100+90+30=400

Day2考得比Day1好[吐血]