洛谷 P4012 深海机器人问题【费用流】

  1 #include<bits/stdc++.h>
  2 using namespace std;
  3 typedef long long ll;
  4 const int N = 455;
  5 const int M = N*4+30;
  6 const int INF = 0x3f3f3f3f;
  7 struct Edge { int to,next,cap,flow,cost; }edge[M];
  8 int head[N],tol;
  9 int pre[N],dis[N];
 10 bool vis[N];
 11 int V;      
 12 void init(int n) {
 13     V = n;
 14     tol = 0;
 15     memset(head,-1,sizeof(head));
 16 }
 17 void addedge(int u,int v,int cap,int cost) {
 18     edge[tol].to = v; edge[tol].cap = cap; edge[tol].cost = cost; edge[tol].flow = 0; edge[tol].next = head[u]; head[u] = tol++;
 19     edge[tol].to = u; edge[tol].cap = 0; edge[tol].cost = -cost; edge[tol].flow = 0; edge[tol].next = head[v]; head[v] = tol++;
 20 }
 21 bool spfa(int s,int t) {
 22     queue<int>q;
 23     for(int i = 0;i < V;i++) {
 24         dis[i] = INF;
 25         vis[i] = false;
 26         pre[i] = -1;
 27     }
 28     dis[s] = 0;
 29     vis[s] = true;
 30     q.push(s);
 31     while(!q.empty()) {
 32         int u = q.front();
 33         q.pop();
 34         vis[u] = false;
 35         for(int i = head[u]; i != -1;i = edge[i].next) {
 36             int v = edge[i].to;
 37             if(edge[i].cap > edge[i].flow && dis[v] > dis[u] + edge[i].cost ) {
 38                 dis[v] = dis[u] + edge[i].cost;
 39                 pre[v] = i;
 40                 if(!vis[v]) {
 41                     vis[v] = true;
 42                     q.push(v);
 43                 }
 44             }
 45         }
 46     }
 47     if(pre[t] == -1) return false;
 48     else return true;
 49 }
 50 int minCostMaxflow(int s,int t,int &cost) {
 51     int flow = 0;
 52     cost = 0;
 53     while(spfa(s,t)) {
 54         int Min = INF;
 55         for(int i = pre[t];i != -1;i = pre[edge[i^1].to]) {
 56             if(Min > edge[i].cap - edge[i].flow)
 57                 Min = edge[i].cap - edge[i].flow;
 58         }
 59         for(int i = pre[t];i != -1;i = pre[edge[i^1].to]) {
 60             edge[i].flow += Min;
 61             edge[i^1].flow -= Min;
 62             cost += edge[i].cost * Min;
 63         }
 64         flow += Min;
 65     }
 66     return flow;
 67 }
 68 int main() {
 69     int a, b, p, q, k, x, y, i, j, ans = 0;
 70     scanf("%d%d", &a, &b);//出发和目的地数目
 71     scanf("%d%d", &p, &q);
 72     init((p+1)*(q+1)+3);
 73 
 74     int s = (p+1)*(q+1)+1, t = (p+1)*(q+1)+2;
 75 
 76     for(i = 0; i <= p; ++i) {//p+1行,向东移动
 77         for(j = 0; j < q; ++j) {
 78             scanf("%d", &x);//边上的标本价值
 79             addedge(i*(q+1)+j, i*(q+1)+j+1, 1, -x);
 80             addedge(i*(q+1)+j, i*(q+1)+j+1, INF, 0);
 81         }
 82     }
 83     for(j = 0; j <= q; ++j) {//q+1列,向北移动
 84         for(i = 0; i < p; ++i) {
 85             scanf("%d", &x);
 86             addedge(i*(q+1)+j, i*(q+1)+j+q+1, 1, -x);
 87             addedge(i*(q+1)+j, i*(q+1)+j+q+1, INF, 0);
 88         }
 89     }
 90     for(i = 1; i <= a; ++i) {//起点
 91         scanf("%d%d%d", &k, &x, &y);
 92         addedge(s, x*(q+1)+y, k, 0);
 93     }
 94     for(i = 1; i <= b; ++i) {//终点
 95         scanf("%d%d%d", &k, &x, &y);
 96         addedge(x*(q+1)+y, t, k, 0);
 97     }
 98     minCostMaxflow(s, t, ans);
 99     printf("%d\n", -ans);
100     return 0;
101 }