Tachibana Kanade And Dream City

C++14(g++5.4) 解法, 执行用时: 161ms, 内存消耗: 2664K, 提交时间: 2020-04-10 21:12:26

#include <stdio.h>
#include <algorithm>
#include <queue>
#include <string.h>
#define int long long
#define ll long long
using namespace std; 
const int N=410,M=100010;
int head[N],ver[M],nex[M],pre[N],dep[N],w[M];
ll f[210][210],val[210],c[210];
int n,m,s,t,tot,maxflow;
ll sum;
void add(int u,int v,int d)
{
	ver[++tot]=v;nex[tot]=head[u];w[tot]=d;head[u]=tot;
}
bool bfs()
{
	memset(dep,0,sizeof(dep));
	queue<int>q;
	q.push(s);dep[s]=1;
	while(q.size())
	{
		int u=q.front();q.pop();
		for(int i=head[u];i;i=nex[i])
		{
			int v=ver[i];
			if(dep[v]||!w[i])continue;
			dep[v]=dep[u]+1;
			q.push(v);
			if(v==t)return 1;	
		}	
	}
	return 0;
}
int dinic(int u,int flow)
{
	if(u==t)return flow;
	int res=flow,k;
	for(int i=head[u];i&&res;i=nex[i])
	{
		int v=ver[i];
		if(w[i]&&dep[v]==dep[u]+1)
		{
			k=dinic(v,min(res,w[i]));
			if(!k)dep[v]=0;
			w[i]-=k;w[i^1]+=k;
			res-=k;
		}
	}
	return flow-res;
}
void floyd()
{
	for(int k=1;k<=n;k++)
		for(int i=1;i<=n;i++)
			for(int j=1;j<=n;j++)
				f[i][j]=min(f[i][j],f[i][k]+f[k][j]);
}
bool check(ll mid)
{
	memset(head,0,sizeof(head));
	tot=1;ll maxflow=0;
	for(int i=1;i<=n;i++)add(s,i,val[i]),add(i,s,0),add(i,i+n,1e9),add(i+n,i,0),add(i+n,t,c[i]),add(t,i+n,0);
	for(int i=1;i<=n;i++)
		for(int j=1;j<=n;j++)
			if(f[i][j]<=mid&&i!=j)add(i,j+n,1e9),add(j+n,i,0);
	int flow=0;
	while(bfs())
		while(flow=dinic(s,1e18))maxflow+=flow;
	return maxflow>=sum;
}
ll solve()
{
	ll l=0,r=1e18;
	while(l<r)
	{
		ll mid=(l+r)/2;
		if(check(mid))r=mid;
		else l=mid+1;
	}
	if(r==1e18)return -1;
	return l;
}
signed main()
{
	scanf("%lld%lld",&n,&m);
	s=0,t=2*n+1;
	memset(f,0x3f,sizeof(f));
	for(int i=1;i<=n;i++)scanf("%lld%lld",&val[i],&c[i]),sum+=val[i];
	for(int i=1;i<=m;i++)
	{
		int u,v,z;
		scanf("%lld%lld%lld",&u,&v,&z);
		f[u][v]=f[v][u]=min(f[u][v],z);
	}
	floyd();
	printf("%lld\n",solve());
}

C++11(clang++ 3.9) 解法, 执行用时: 178ms, 内存消耗: 2784K, 提交时间: 2019-09-26 00:26:39

#pragma GCC optimize(2)
#include<bits/stdc++.h>
#define int long long
using namespace std;
const int inf=0x3f3f3f3f3f3f3f3f;
const int N=1e4+10,M=1e5+10;
int n,m,g[210][210],s,t,h[N],res,v[N],val[N];
int head[N],nex[M],to[M],w[M],tot=1;
inline void ade(int a,int b,int c){
	to[++tot]=b; w[tot]=c; nex[tot]=head[a]; head[a]=tot;
}
inline void add(int a,int b,int c){
	ade(a,b,c);	ade(b,a,0);
}
void floyd(){
	for(int k=1;k<=n;k++)
		for(int i=1;i<=n;i++)
			for(int j=1;j<=n;j++)	g[i][j]=min(g[i][j],g[i][k]+g[k][j]);
}
int bfs(){
	memset(h,0,sizeof h); h[s]=1; queue<int> q;	q.push(s);
	while(q.size()){
		int u=q.front();	q.pop();
		for(int i=head[u];i;i=nex[i]){
			if(w[i]&&!h[to[i]]){
				h[to[i]]=h[u]+1;	q.push(to[i]);
			}
		}
	}
	return h[t];
}
int dfs(int x,int f){
	if(x==t)	return f; int fl=0;
	for(int i=head[x];i&&f;i=nex[i]){
		if(w[i]&&h[to[i]]==h[x]+1){
			int mi=dfs(to[i],min(f,w[i]));
			w[i]-=mi; w[i^1]+=mi; fl+=mi; f-=mi;
		}
	}
	if(!fl)	h[x]=-1;
	return fl;
}
int dinic(){
	int res=0;
	while(bfs())	res+=dfs(s,inf);
	return res;
}
int check(int mid){
	tot=1;	memset(head,0,sizeof head);
	for(int i=1;i<=n;i++)	add(s,i,v[i]),add(i,i+n,1e9),add(i+n,t,val[i]);
	for(int i=1;i<=n;i++)
		for(int j=1;j<=n;j++)	if(g[i][j]<=mid&&i!=j){
			add(i,j+n,1e9);
		}
	return dinic()>=res;
}
int bsearch(){
	int l=1,r=1e18;
	while(l<r){
		int mid=l+r>>1;
		if(check(mid))	r=mid;
		else	l=mid+1;
	}
	if(r==1e18)	return -1;
	else	return l;
}
signed main(){
	cin>>n>>m;	t=n*2+1;	memset(g,0x3f,sizeof g);
	for(int i=1;i<=n;i++)	cin>>v[i]>>val[i],res+=v[i]; 
	while(m--){
		int a,b,c;	cin>>a>>b>>c;	g[a][b]=g[b][a]=min(g[a][b],c);
	}
	floyd();
	cout<<bsearch()<<endl;
	return 0;
}

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