poj 3160 spfa+tarjan 无向图最值问题

#include<iostream>
#include<cstring>
#include<algorithm>
#include<cstdio>
#include<vector>
#include<sstream>
#include<string>
#include<climits>
#include<set>
#include<bitset>
#include<cmath>
#include<deque>
#include<map>
#include<queue>
#define iinf 2000000000
#define linf 1000000000000000000LL
#define dinf 1e200
#define all(v) (v).begin(),(v).end()
#define sz(x) x.size()
#define pb push_back
#define mp make_pair
#define lng long long
#define sqr(a) ((a)*(a))
#define pii pair<int,int>
#define pll pair<lng,lng>
#define pss pair<string,string>
#define pdd pair<double,double>
#define X first
#define Y second
#define pi 3.14159265359
#define ff(i,xi,n) for(int i=xi;i<=(int)(n);++i)
#define ffd(i,xi,n) for(int i=xi;i>=(int)(n);--i)
#define ffl(i,r) for(int i=head[r];i!=-1;i=edge[i].next)
#define cc(i,j) memset(i,j,sizeof(i))
#define N 50000
#define M 4000000
using namespace std;
typedef vector<int> vi;
typedef vector<string> vs;
typedef unsigned int uint;
typedef unsigned lng ulng;
template<class T> inline void checkmax(T &x,T y){if(x<y) x=y;}
template<class T> inline void checkmin(T &x,T y){if(x>y) x=y;}
template<class T> inline T Min(T x,T y){return (x>y?y:x);}
template<class T> inline T Max(T x,T y){return (x<y?y:x);}
template<class T> T gcd(T a,T b){return (a%b)==0?b:gcd(b,a%b);}
template<class T> T lcm(T a,T b){return a*b/gcd(a,b);}
queue<int> q;
bool in
;
struct pp{int v,w,next;}edge[M];int tot=0,root,price
,cost
,head
,newhead
,n,m,Index,od
,ind
,hash
,pre
,nn,low
,id
,stack
,top,ans
;
inline void addedge(int u,int v,int w,int *h){edge[tot].v=v,edge[tot].w=w,edge[tot].next=h[u],h[u]=tot++;}
void dfs(int r)
{
pre[r]=low[r]=++Index;
stack[++top]=r;
ffl(i,r)
{
int v=edge[i].v;
if(pre[v]==-1)
{
dfs(v);
checkmin(low[r],low[v]);
}
else
if(id[v]==-1)
checkmin(low[r],pre[v]);
}
if(pre[r]==low[r])
{
int v;
++nn;
do
{
v=stack[top--];
id[v]=nn;
}while(v!=r);
}
}
int main()
{
#ifdef DEBUG
// freopen("data.in","r",stdin);
// freopen("data.out","w",stdout);
#endif
while(scanf("%d%d",&n,&m)==2)
{
cc(pre,-1);cc(low,-1);cc(head,-1);cc(id,-1);cc(ind,0);top=0;tot=0;Index=0;cc(newhead,-1);nn=0;
ff(i,0,n-1) {scanf("%d",&price[i]);if(price[i]<0) price[i]=0;}
ff(i,1,m)
{
int u,v;
scanf("%d%d",&u,&v);
addedge(u,v,0,head);
}
ff(i,0,n-1)
if(pre[i]==-1) dfs(i);
cc(hash,-1);cc(od,0);
ff(i,0,n-1)
ffl(j,i)
{
int v=edge[j].v;
if(hash[id[i]]!=id[v]&&id[i]!=id[v])
addedge(id[i],id[v],0,newhead),hash[id[i]]=id[v],ind[id[v]]++,od[id[i]]++;
}
cc(cost,0);
ff(i,0,n-1)
cost[id[i]]+=price[i];
while(!q.empty())
q.pop();
cc(in,0);
ff(i,1,nn)
{if(ind[i]==0) addedge(0,i,0,newhead);
ans[i]=-iinf;
}
ans[0]=0;
q.push(0);
in[0]=1;
while(!q.empty())
{
int u=q.front();
q.pop();
in[u]=0;
for(int i=newhead[u];i!=-1;i=edge[i].next)
{
int v=edge[i].v;
if(ans[u]+cost[v]>ans[v])
{
ans[v]=ans[u]+cost[v];
if(!in[v]) q.push(v),in[v]=1;
}
}
}
int res=-iinf;
ff(i,1,nn)
if(od[i]==0)checkmax(res,ans[i]);
printf("%d\n",res);
}
return 0;
}
/*
made by qinggege
*/