题目
题解

Solution

spfa找正环

Code

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int b[102][1002],s[102][1002],i,j,k,K,tot,n,m,mp[102][102],q[990001],L[102],x,y,z,l,r,mid,T[102][1002],ans;
ll dis[102];
bool vis[102];
inline char gc(){
	static char buf[100000],*p1=buf,*p2=buf;
	return p1==p2&&(p2=(p1=buf)+fread(buf,1,100000,stdin),p1==p2)?EOF:*p1++;
}
inline int rd(){
	int x=0,fl=1;char ch=gc();
	for (;ch<48||ch>57;ch=gc())if(ch=='-')fl=-1;
	for (;48<=ch&&ch<=57;ch=gc())x=(x<<3)+(x<<1)+(ch^48);
	return x*fl;
}
bool chk(int x){
	memset(L,0,(n+1)<<2);
	memset(dis,0,(n+1)<<3);
	int h=0,t=0;
	for (int i=1;i<=n;i++) q[t++]=i,vis[i]=1;
	while (h<t){
		int u=q[h++];vis[u]=0;
		for (int i=1;i<=n;i++)
			if (dis[i]<=dis[u]+T[u][i]-1ll*x*mp[u][i]){
				dis[i]=dis[u]+T[u][i]-1ll*x*mp[u][i];
				if (!vis[i]){
					if ((++L[i])==n) return 1;
					vis[i]=1,q[t++]=i;
				}
			}
	}
	return 0;
}
int main(){
	n=rd();m=rd();K=rd();
	memset(mp,63,sizeof(mp));
	for (i=1;i<=n;i++)
		for (j=1;j<=K;j++) b[i][j]=rd(),s[i][j]=rd();
	for (i=1;i<=n;i++)
		for (j=1;j<=n;j++)
			for (k=1;k<=K;k++)
				if (b[i][k]!=-1 && s[j][k]!=-1) T[i][j]=max(T[i][j],s[j][k]-b[i][k]);
	for (i=1;i<=m;i++) x=rd(),y=rd(),z=rd(),mp[x][y]=min(mp[x][y],z);
	for (k=1;k<=n;k++)
		for (i=1;i<=n;r=max(r,mp[i][j]),i++)
			for (j=1;j<=n;j++) mp[i][j]=min(mp[i][j],mp[i][k]+mp[k][j]);
	while (l<=r){
		mid=l+r>>1;
		if (chk(mid)) ans=mid,l=mid+1;
		else r=mid-1;
	}
	printf("%d",ans);
}