• P3705 [SDOI2017]新生舞会 分数规划 费用流


    #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>
    
    /*
            
    ⊂_ヽ
      \\ Λ_Λ  来了老弟
       \('ㅅ')
        > ⌒ヽ
       /   へ\
       /  / \\
       レ ノ   ヽ_つ
      / /
      / /|
     ( (ヽ
     | |、\
     | 丿 \ ⌒)
     | |  ) /
    'ノ )  Lノ
    
    */
    
    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 boost ios::sync_with_stdio(false);cin.tie(0)
    #define rep(a, b, c) for(int a = (b); a <= (c); ++ a)
    #define max3(a,b,c) max(max(a,b), c);
    #define min3(a,b,c) min(min(a,b), c);
    
    
    const ll oo = 1ll<<17;
    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;
    }
    struct FastIO {
        static const int S = 4e6;
        int wpos;
        char wbuf[S];
        FastIO() : wpos(0) {}
        inline int xchar() {
            static char buf[S];
            static int len = 0, pos = 0;
            if (pos == len)
                pos = 0, len = fread(buf, 1, S, stdin);
            if (pos == len) exit(0);
            return buf[pos++];
        }
        inline int xuint() {
            int c = xchar(), x = 0;
            while (c <= 32) c = xchar();
            for (; '0' <= c && c <= '9'; c = xchar()) x = x * 10 + c - '0';
            return x;
        }
        inline int xint()
        {
            int s = 1, c = xchar(), x = 0;
            while (c <= 32) c = xchar();
            if (c == '-') s = -1, c = xchar();
            for (; '0' <= c && c <= '9'; c = xchar()) x = x * 10 + c - '0';
            return x * s;
        }
        inline void xstring(char *s)
        {
            int c = xchar();
            while (c <= 32) c = xchar();
            for (; c > 32; c = xchar()) * s++ = c;
            *s = 0;
        }
        inline void wchar(int x)
        {
            if (wpos == S) fwrite(wbuf, 1, S, stdout), wpos = 0;
            wbuf[wpos++] = x;
        }
        inline void wint(int x)
        {
            if (x < 0) wchar('-'), x = -x;
            char s[24];
            int n = 0;
            while (x || !n) s[n++] = '0' + x % 10, x /= 10;
            while (n--) wchar(s[n]);
            wchar('
    ');
        }
        inline void wstring(const char *s)
        {
            while (*s) wchar(*s++);
        }
        ~FastIO()
        {
            if (wpos) fwrite(wbuf, 1, wpos, stdout), wpos = 0;
        }
    } io;   
    inline void cmax(int &x,int y){if(x<y)x=y;}
    inline void cmax(ll &x,ll y){if(x<y)x=y;}
    inline void cmin(int &x,int y){if(x>y)x=y;}
    inline void cmin(ll &x,ll y){if(x>y)x=y;}
    
    /*-----------------------showtime----------------------*/
                const int maxn = 209;
                int n;
                int a[maxn][maxn],b[maxn][maxn];
    
                struct E{
                    int v,val;
                    double cost;
                    int nxt;
                }edge[maxn*maxn];
                
                int head[maxn],gtot = 0;
                void addedge(int u,int v,int val,double cost){
                    edge[gtot].v = v;
                    edge[gtot].val = val;
                    edge[gtot].cost = cost;
                    edge[gtot].nxt = head[u];
                    head[u] = gtot++;
    
                    edge[gtot].v = u;
                    edge[gtot].val = 0;
                    edge[gtot].cost = -cost;
                    edge[gtot].nxt = head[v];
                    head[v] = gtot++;   
                }
    
                double dis[maxn];
                int vis[maxn],pre[maxn],path[maxn];
                bool spfa(int s,int t){
                    for(int i=s; i <=t; i++) dis[i] = 1000000000.0;
                    memset(pre, -1, sizeof(pre));
                    memset(vis, 0, sizeof(vis));
                    queue<int>que;
                    que.push(s); vis[s] = 1;
                    dis[s] = 0.0;
                    while(!que.empty()){
                        int u = que.front(); que.pop();
                        vis[u] = 0;
                        for(int i=head[u]; ~i; i = edge[i].nxt){
                            int v = edge[i].v, val = edge[i].val;
                            double cost = edge[i].cost;
                            if(val > 0 && dis[v] > dis[u] + cost){
                                dis[v] = dis[u] + cost;
                                pre[v] = u; path[v] = i;
                                if(vis[v] == 0){
                                    que.push(v);
                                    vis[v] = 1;
                                }
                            }
                        }
                    }
                    return pre[t] != -1;
                }
                double mcmf(int s,int t){
                    int flow = 0;
                    double cost = 0;
                    while(spfa(s, t)){
                        int f = inf;
                        for(int i=t; i!=s; i=pre[i]){
                            f = min(f, edge[path[i]].val);
                        }
                        flow += f;
                        cost = cost + 1.0*f*dis[t];
                        for(int i=t; i!=s; i=pre[i]){
                            edge[path[i]].val -=f;
                            edge[path[i]^1].val += f;
                        }
                    }
                    return cost;
                }
                bool check(double c){
                    memset(head, -1, sizeof(head));
                    gtot = 0;
                    int s = 0, t = n+n+1;
                    for(int i=1; i<=n; i++) {
                        addedge(s, i, 1, 0);
                        for(int j=1; j<=n; j++){
                            addedge(i, j+n, 1, 1.0*c * b[i][j] - 1.0*a[i][j]);
                        }
                        addedge(i+n, t, 1, 0);  
                    }
                    return mcmf(s, t) < 0.0;
                }
    int main(){
                n = io.xint();
                rep(i, 1, n) rep(j,1,n) a[i][j] = io.xint() ;
                rep(i, 1, n) rep(j,1,n) b[i][j] = io.xint();
                double le = 0,ri = 1000000;
                while(abs(ri - le) > esp){
    
                    double mid = (le + ri)*1.0/2.0;
               //     debug(mid);
                    if(check(mid)) le = mid;
                    else ri = mid;
                }
                printf("%.6f
    ", le);
    
                return 0;
    }
    View Code
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  • 原文地址:https://www.cnblogs.com/ckxkexing/p/10393506.html
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