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  • 洛谷P2050 [NOI2012]美食节

    动态加边网络流

      1 #include<cstdio>
      2 #include<cstdlib>
      3 #include<algorithm>
      4 #include<cstring>
      5 #include<vector>
      6 #include<queue>
      7 #define rint register int
      8 #define ll int
      9 #define MAXN 100005+10
     10 #define pb push_back
     11 #define INF 0x7f7f7f7f
     12 #define oo 0x7f7f7f7f7f7f7f7f
     13 #define pil pair<int,ll>
     14 #define mp make_pair
     15 #define ft first
     16 #define sc second
     17 using namespace std;
     18 int read(){
     19     int x=0,f=1;char ch=getchar();
     20     while(ch<'0'||ch>'9'){if('-'==ch)f=-1;ch=getchar();}
     21     while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
     22     return x*f;
     23 }
     24 struct E{
     25     int from,to,cap,flow;
     26     ll cost;
     27     E(int x=0,int y=0,int c=0,int f=0,ll w=0LL){
     28         from=x,to=y,cap=c,flow=f,cost=w;
     29     }
     30 };
     31 int N,M,s,t=MAXN-1;
     32 vector<E> es;
     33 vector<int> G[MAXN];
     34 void add(int x,int y,int cap,ll cost){
     35     es.pb(E(x,y,cap,0,cost));
     36     es.pb(E(y,x,0,0,-cost));
     37     M=es.size();
     38     G[x].pb(M-2),G[y].pb(M-1);
     39 }
     40 int p[MAXN],a[MAXN];
     41 ll d[MAXN];
     42 int b[MAXN];
     43 bool SPFA(int &flow,ll &cost){
     44     p[s]=0,a[s]=INF;
     45     memset(d,0x7f,sizeof(d));
     46     d[s]=0;
     47     memset(b,0,sizeof(b));
     48     b[s]=1;
     49     queue<int> q;
     50     q.push(s);
     51     while(!q.empty()){
     52         int x=q.front();q.pop();b[x]=0;
     53         for(rint i=0;i<G[x].size();i++){
     54             E &e=es[G[x][i]];
     55             if(e.cap>e.flow&&d[e.to]>d[x]+e.cost){
     56                 p[e.to]=G[x][i];
     57                 a[e.to]=min(a[x],e.cap-e.flow);
     58                 d[e.to]=d[x]+e.cost;
     59                 if(!b[e.to]){
     60                     b[e.to]=1;
     61                     q.push(e.to);
     62                 }
     63             }
     64         }
     65     }
     66     if(oo==d[t]){
     67         return 0;
     68     }
     69     flow+=a[t];
     70     cost+=a[t]*d[t];
     71     for(rint i=t;i!=s;i=es[p[i]].from){
     72         es[p[i]].flow+=a[t];
     73         es[p[i]^1].flow-=a[t];
     74     }
     75     return 1;
     76 }
     77 pil MaxfMinc(){
     78     int flow=0;
     79     ll cost=0LL;
     80     while(SPFA(flow,cost));
     81     return mp(flow,cost);
     82 }
     83 int n,m;
     84 int P[45],T[45][105],now[105];
     85 int sum,L;
     86 int cook[MAXN],cnt[MAXN];
     87 int id[105][805];
     88 int work(int x,int y){
     89     add(id[x][y],t,1,0);
     90     for(rint i=1;i<=n;i++){
     91         add(L+i,id[x][y],1,T[i][x]*y);
     92     }    
     93 }
     94 void init(){
     95     n=read(),m=read();
     96     for(rint i=1;i<=n;i++){
     97         P[i]=read();
     98         sum+=P[i];
     99     }
    100     for(rint i=1;i<=n;i++){
    101         for(rint j=1;j<=m;j++){
    102             T[i][j]=read();
    103         }
    104     }
    105     L=m*sum;
    106     int idx=0;
    107     for(rint i=1;i<=m;i++){
    108         for(rint j=1;j<=sum;j++){
    109             id[i][j]=++idx;
    110             cook[idx]=i,cnt[idx]=j;
    111         }
    112     }
    113     for(rint i=1;i<=n;i++){
    114         add(s,L+i,P[i],0);
    115     }
    116     for(rint i=1;i<=m;i++){
    117         work(i,1);
    118         now[i]=1;
    119     }    
    120 }
    121 void solve(){123     int flow=0;ll cost=0LL;
    124     while(SPFA(flow,cost)){
    125         if(flow==sum){
    126             printf("%lld
    ",cost);
    127             break;
    128         }
    129         int x=es[p[t]].from;
    130         now[cook[x]]++;
    131         work(cook[x],now[cook[x]]);
    132     }
    133 }
    134 int main()
    135 {
    136 //    freopen("data.in","r",stdin); 
    137     init();
    138     solve();
    139     return 0;
    140 }
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  • 原文地址:https://www.cnblogs.com/w-h-h/p/8454363.html
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