poj 2391 floyd + 二分搜索 + 拆点建图 + dinic

神题！！！！！！！！

尼玛难想就算了，还wa了！！wa比tle可怕啊！！tle肯定是什么地方发生了很明显的错误。。wa了的话那就坑爹了，刷网络流真怕wa啊！！最后想起来是inf64那个地方少减了一个1。。。多么不明显的错误啊，找了这么久啊，我还不如重敲一遍算了！

/*------------------------------------------------------------------------------

------------------------------------------------------------------------------*/
#include<iostream>
#include<vector>
#include<algorithm>
#include<cstdio>
#include<queue>
#include<stack>
#include<string>
#include<map>
#include<set>
#include<cmath>
#include<cassert>
#include<cstring>
#include<iomanip>
using namespace std;

#ifdef _WIN32
#define i64 __int64
#define out64 "%I64d\n"
#define in64 "%I64d"
#else
#define i64 long long
#define out64 "%lld\n"
#define in64 "%lld"
#endif


#define FOR(i,a,b)      for( int i = (a) ; i <= (b) ; i ++)
#define FF(i,a)         for( int i = 0 ; i < (a) ; i ++)
#define FFD(i,a)        for( int i = (a)-1 ; i >= 0 ; i --)
#define S64(a)          scanf(in64,&a)
#define SS(a)           scanf("%d",&a)
#define LL(a)           ((a)<<1)
#define RR(a)           (((a)<<1)+1)
#define SZ(a)           ((int)a.size())
#define PP(n,m,a)		puts("---");FF(i,n){FF(j,m)cout << a[i][j] << ' ';puts("");}
#define pb              push_back
#define CL(Q)           while(!Q.empty())Q.pop()
#define MM(name,what)   memset(name,what,sizeof(name))
#define read            freopen("in.txt","r",stdin)
#define write           freopen("out.txt","w",stdout)

const int inf=0x3f3f3f3f;
const i64 inf64 = 0x3f3f3f3f3f3f3f3fLL;
const double oo = 10e9;
const double eps = 10e-8;
const double pi = acos(-1.0);
const int maxn=222;
const int maxc=444;

struct zz
{
    int from;
    int to;
    int c;
    int id;
}zx,tz;
vector<zz>g[maxc];
queue<int>q;
int have[maxn];
int can[maxn];
int cen[maxc];
i64 a[maxn][maxn];
int tx,ty,n,m,end,total;
i64 need,l,r;

inline void floyd()    
{
    FOR(k,1,n)FOR(i,1,n)FOR(j,1,n)a[i][j]=a[i][k]+a[k][j]<a[i][j]?a[i][k]+a[k][j]:a[i][j];    
    return ;
}

void build(i64 x)
{   
    FF(i,maxc) g[i].clear(); 
    FOR(i,1,n) 
    {   
        zx.from = 0;
        zx.to = i;
        zx.c = have[i];
        zx.id = g[i].size(); 
        g[0].pb(zx);
        swap(zx.from,zx.to);
        zx.c = 0;
        zx.id = g[0].size()-1;
        g[i].pb(zx);            
    }        
    FOR(i,1,n) FOR(j,1,n)
    {
        if(a[i][j] <= x)    
        {
            zx.from = i;
            zx.to = j+n;
            zx.c = inf;       
            zx.id = g[j+n].size();      
            g[i].pb(zx);
            swap(zx.from,zx.to);
            zx.c = 0;
            zx.id = g[i].size() - 1;
            g[j+n].pb(zx);
        } 
    }    
    FOR(i,1,n)
    {
        zx.from = i+n;
        zx.to = end;
        zx.c = can[i];
        zx.id = g[end].size();
        g[i+n].pb(zx);
        swap(zx.from,zx.to);
        zx.c = 0;
        zx.id = g[i+n].size() - 1;
        g[end].pb(zx);
    }             
    return ;
}

bool bfs()
{
    MM(cen,-1);
    CL(q);
    q.push(0);
    cen[0]=0;
    int now,to;
    while(!q.empty())
    {   
        now=q.front();
        q.pop();
        FF(i,g[now].size())
        {
            to=g[now][i].to;
            if(g[now][i].c > 0 && cen[to] == -1 )
            {
                cen[to] = cen[now] + 1;
                q.push(to);
            }
        }
    }    
    return cen[end] != -1;
}   

int dfs(int flow = inf, int now = 0 )
{                           
    if(now == end )
    {
        return flow;
    }                   
    int temp,sum=0;
    int to;
    FF(i,g[now].size())
    {
        to = g[now][i].to;
        if( cen[to] - cen[now] == 1 && flow > sum && g[now][i].c > 0 ) 
        {
            temp = dfs ( min ( g[now][i].c , flow - sum ) , to );
            sum += temp;
            g[now][i].c -= temp;
            g[to][g[now][i].id].c += temp;
        }
    }
    if(!sum) cen[now] = -1;  
    return sum;
}

bool dinic()
{
    int ans=0;
    while( bfs() )
    {
        ans += dfs();
    } 
    if(ans == total)
    {
        return true;
    }
    else
    {
        return false;
    }
}

i64 bin()
{   
    l=0;
    FOR(i,1,n) FOR(j,1,n)
    {
        if(a[i][j]==inf64) continue;
        r = a[i][j]>r ? a[i][j] : r;  
    } 
    build(inf64-1);    // 就是这里，哥太不小心了。。。
    if(!dinic())
    {
        return -1;
    }
    i64 mid;
    while(l < r)
    {   
        mid = (l+r) / 2;
        build(mid);
        if( dinic() ) 
        {
            r = mid;    
        }   
        else
        {
            l = mid + 1;
        }    
    }
    return l;
}


int main()
{
    while(cin>>n>>m)
    {               
        end = 2*n+1;
        total = 0;
        FF(i,maxn) FF(j,maxn)
        {
            a[i][j] = inf64; 
        }
        FOR(i,1,n) a[i][i]=0;
        FOR(i,1,n)
        {
            SS(have[i]);
            total += have[i];
            SS(can[i]);
        }
        FOR(i,1,m)
        {
            SS(tx);SS(ty);
            S64(need);
            if(a[tx][ty] > need)
            {
                a[ty][tx]=a[tx][ty]=need;       
            }                       
        }
        floyd();
        cout<<bin()<<endl;
    }    
    return 0;   
}