• POJ


    传送门:poj.org/problem?id=2516

    题意:

      有m个仓库,n个买家,k个商品,每个仓库运送不同商品到不同买家的路费是不同的。问为了满足不同买家的订单的最小的花费。

    思路:

      设立一个源点S和汇点T,从源点S到每个仓库(1~m)连上容量为商品A的库存、费用为0的边,每个仓库再向每个不同的买家连上容量inf,费用为路费的边、每个顾客向汇点连一条容量为自己对商品A的需求个数、费用为0的边。跑一边费用流即可。这只有运送一个商品的费用,对,那我们就对不同商品建不同的图,一共跑K边,累计答案即可。

      自己一直在想建图,怎么一次就跑出费用。感觉上面的思路和多开一维的观点差不多。

    //#pragma GCC optimize(3)
    //#pragma comment(linker, "/STACK:102400000,102400000")  //c++
    // #pragma GCC diagnostic error "-std=c++11"
    // #pragma comment(linker, "/stack:200000000")
    // #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
    // #pragma GCC optimize("-fdelete-null-pointer-checks,inline-functions-called-once,-funsafe-loop-optimizations,-fexpensive-optimizations,-foptimize-sibling-calls,-ftree-switch-conversion,-finline-small-functions,inline-small-functions,-frerun-cse-after-loop,-fhoist-adjacent-loads,-findirect-inlining,-freorder-functions,no-stack-protector,-fpartial-inlining,-fsched-interblock,-fcse-follow-jumps,-fcse-skip-blocks,-falign-functions,-fstrict-overflow,-fstrict-aliasing,-fschedule-insns2,-ftree-tail-merge,inline-functions,-fschedule-insns,-freorder-blocks,-fwhole-program,-funroll-loops,-fthread-jumps,-fcrossjumping,-fcaller-saves,-fdevirtualize,-falign-labels,-falign-loops,-falign-jumps,unroll-loops,-fsched-spec,-ffast-math,Ofast,inline,-fgcse,-fgcse-lm,-fipa-sra,-ftree-pre,-ftree-vrp,-fpeephole2",3)
    
    #include <algorithm>
    #include  <iterator>
    #include  <iostream>
    #include   <cstring>
    #include   <cstdlib>
    #include   <iomanip>
    #include    <bitset>
    #include    <cctype>
    #include    <cstdio>
    #include    <string>
    #include    <vector>
    #include     <stack>
    #include     <cmath>
    #include     <queue>
    #include      <list>
    #include       <map>
    #include       <set>
    #include   <cassert>
    
    using namespace std;
    #define lson (l , mid , rt << 1)
    #define rson (mid + 1 , r , rt << 1 | 1)
    #define debug(x) cerr << #x << " = " << x << "
    ";
    #define pb push_back
    #define pq priority_queue
    
    
    
    typedef long long ll;
    typedef unsigned long long ull;
    //typedef __int128 bll;
    typedef pair<ll ,ll > pll;
    typedef pair<int ,int > pii;
    typedef pair<int,pii> p3;
    
    //priority_queue<int> q;//这是一个大根堆q
    //priority_queue<int,vector<int>,greater<int> >q;//这是一个小根堆q
    #define fi first
    #define se second
    //#define endl '
    '
    
    #define OKC ios::sync_with_stdio(false);cin.tie(0)
    #define FT(A,B,C) for(int A=B;A <= C;++A)  //用来压行
    #define REP(i , j , k)  for(int i = j ; i <  k ; ++i)
    #define max3(a,b,c) max(max(a,b), c);
    //priority_queue<int ,vector<int>, greater<int> >que;
    
    const ll mos = 0x7FFFFFFF;  //2147483647
    const ll nmos = 0x80000000;  //-2147483648
    const int inf = 0x3f3f3f3f;
    const ll inff = 0x3f3f3f3f3f3f3f3f; //18
    const int mod = 1e9+7;
    const double esp = 1e-8;
    const double PI=acos(-1.0);
    const double PHI=0.61803399;    //黄金分割点
    const double tPHI=0.38196601;
    
    
    template<typename T>
    inline T read(T&x){
        x=0;int f=0;char ch=getchar();
        while (ch<'0'||ch>'9') f|=(ch=='-'),ch=getchar();
        while (ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();
        return x=f?-x:x;
    }
    
    
    /*-----------------------showtime----------------------*/
            const int maxn = 200;
            int n,m,k,x;
            int req[maxn][maxn],hav[maxn][maxn],fy[maxn][maxn][maxn];
            int res[maxn];
    
            const int maxl = 1e6+9;
            struct Edge{
                int to,val,cost,nxt;
            }gEdge[maxl];
    
            int h[maxn],gPre[maxn];
            int gPath[maxl],gDist[maxn];
            bool in[maxn];
            int gcount = 0;
    
            bool spfa(int s,int t){
                memset(gPre,-1,sizeof(gPre));
                memset(gDist, inf,sizeof(gDist));
                memset(in, false, sizeof(in));
    
                gDist[s] = 0; in[s] = true;
                queue<int>q;
                q.push(s);
                while(!q.empty()){
                    int u = q.front();
                    q.pop(); in[u] = false;
                    for(int e = h[u]; e!=-1;e = gEdge[e].nxt){
                        int v = gEdge[e].to, w = gEdge[e].cost;
                        if(gEdge[e].val >  0 && gDist[v] > gDist[u] + w){
                            gDist[v] = gDist[u] + gEdge[e].cost;
                            gPre[v] = u;
                            gPath[v] = e;
                            if(!in[v]){
                                q.push(v); in[v] = true;
                            }
                        }
                    }
                }
                return gPre[t] != -1;
            }
            int MinCostFlow(int s,int t,int nd){
                int cost = 0,flow = 0;
                while(spfa(s,t)){
                    int f = inf;
                    for(int u=t; u!=s; u = gPre[u]){
                        if(gEdge[gPath[u]].val < f){
                            f = gEdge[gPath[u]].val;
                        }
                    }
                    flow +=f;
                    cost += gDist[t]*f;
                    for(int u=t; u!=s; u=gPre[u]){
                        gEdge[gPath[u]].val -= f;
                        gEdge[gPath[u]^1].val += f;
                    }
                }
                if(flow != nd){
                    return -1;
                }
                return cost;
            }
    
            void addedge(int u,int v,int val,int cost){
                gEdge[gcount].to = v;
                gEdge[gcount].val = val;
                gEdge[gcount].cost = cost;
                gEdge[gcount].nxt = h[u];
                h[u] = gcount++;
    
                gEdge[gcount].to = u;
                gEdge[gcount].val = 0;
                gEdge[gcount].cost = -cost;
                gEdge[gcount].nxt = h[v];
                h[v] = gcount++;
            }
    int main(){
            while(~scanf("%d%d%d", &n, &m, &k) && n+m+k){
    
                memset(req,0,sizeof(req));
                memset(hav,0,sizeof(hav));
                memset(res, 0 ,sizeof(res));
    
                for(int i=1; i<=n; i++)
                    for(int j=1; j<=k; j++)
                        scanf("%d", &req[i][j]),res[j] += req[i][j];
    
                for(int i=1; i<=m; i++)
                    for(int j=1; j<=k; j++)
                     {
                        scanf("%d", &hav[i][j]);
                     }
                for(int i=1; i<=k; i++)
                    for(int t = 1; t<=n; t++)
                        for(int j=1; j<=m; j++)
                        {
                            scanf("%d",&fy[i][j][t]);
                        }
                int ans = 0,kk = k,flag = 1;
                int s = 0,t = n+m+1;
                for(int kind = 1; kind <= k; kind ++){
                    memset(h,-1,sizeof(h));
                    gcount = 0;
                    for(int i=1; i<=m; i++) addedge(s,i,hav[i][kind],0);
                    for(int i=1; i<=m; i++)
                        for(int j=1; j<=n; j++){
                                addedge(i,m+j,inf,fy[kind][i][j]);
                        }
                    for(int i=1; i<=n; i++){
                        addedge(m+i,t, req[i][kind],0);
                    }
                    int tmp = MinCostFlow(s,t,res[kind]);
                    if(tmp == -1) flag = 0;
                    else ans += tmp;
                }
                if(flag == 0)puts("-1");
                else
                    printf("%d
    ", ans);
            }
            return 0;
    }
    POJ 2516
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  • 原文地址:https://www.cnblogs.com/ckxkexing/p/9761305.html
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