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  • [CODEVS1915] 分配问题(最小费用最大流)

    传送门

    脑残题

    建图都懒得说了

    ——代码

      1 #include <queue>
      2 #include <cstdio>
      3 #include <cstring>
      4 #include <iostream>
      5 #define N 1000001
      6 #define min(x, y) ((x) < (y) ? (x) : (y))
      7 
      8 int n, cnt, s, t;
      9 int a[101][101], dis[N], pre[N];
     10 int head[N], to[N << 1], val[N << 1], cost[N << 1], next[N << 1];
     11 bool vis[N];
     12 
     13 inline int read()
     14 {
     15     int x = 0, f = 1;
     16     char ch = getchar();
     17     for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -1;
     18     for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - '0';
     19     return x * f;
     20 }
     21 
     22 inline void add(int x, int y, int z, int c)
     23 {
     24     to[cnt] = y;
     25     val[cnt] = z;
     26     cost[cnt] = c;
     27     next[cnt] = head[x];
     28     head[x] = cnt++;
     29 }
     30 
     31 inline bool spfa()
     32 {
     33     int i, u, v;
     34     std::queue <int> q;
     35     memset(vis, 0, sizeof(vis));
     36     memset(pre, -1, sizeof(pre));
     37     memset(dis, 127 / 3, sizeof(dis));
     38     q.push(s);
     39     dis[s] = 0;
     40     while(!q.empty())
     41     {
     42         u = q.front(), q.pop();
     43         vis[u] = 0;
     44         for(i = head[u]; i ^ -1; i = next[i])
     45         {
     46             v = to[i];
     47             if(val[i] && dis[v] > dis[u] + cost[i])
     48             {
     49                 dis[v] = dis[u] + cost[i];
     50                 pre[v] = i;
     51                 if(!vis[v])
     52                 {
     53                     q.push(v);
     54                     vis[v] = 1;
     55                 }
     56             }
     57         }
     58     }
     59     return pre[t] ^ -1;
     60 }
     61 
     62 inline int dinic()
     63 {
     64     int i, d, sum = 0;
     65     while(spfa())
     66     {
     67         d = 1e9;
     68         for(i = pre[t]; i ^ -1; i = pre[to[i ^ 1]]) d = min(d, val[i]);
     69         for(i = pre[t]; i ^ -1; i = pre[to[i ^ 1]])
     70         {
     71             val[i] -= d;
     72             val[i ^ 1] += d;
     73         }
     74         sum += dis[t] * d;
     75     }
     76     return sum;
     77 }
     78 
     79 int main()
     80 {
     81     int i, j, x;
     82     n = read();
     83     s = 0, t = n + n + 1;
     84     memset(head, -1, sizeof(head));
     85     for(i = 1; i <= n; i++)
     86     {
     87         add(s, i, 1, 0);
     88         add(i, s, 0, 0);
     89         add(i + n, t, 1, 0);
     90         add(t, i + n, 0, 0);
     91         for(j = 1; j <= n; j++)
     92         {
     93             a[i][j] = read();
     94             add(i, j + n, 1, a[i][j]);
     95             add(j + n, i, 0, -a[i][j]);
     96         }
     97     }
     98     printf("%d
    ", dinic());
     99     cnt = 0;
    100     memset(head, -1, sizeof(head));
    101     for(i = 1; i <= n; i++)
    102     {
    103         add(s, i, 1, 0);
    104         add(i, s, 0, 0);
    105         add(i + n, t, 1, 0);
    106         add(t, i + n, 0, 0);
    107         for(j = 1; j <= n; j++)
    108         {
    109             add(i, j + n, 1, -a[i][j]);
    110             add(j + n, i, 0, a[i][j]);
    111         }
    112     }
    113     printf("%d
    ", -dinic());
    114     return 0;
    115 }
    View Code
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  • 原文地址:https://www.cnblogs.com/zhenghaotian/p/7007913.html
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