122 lines
2.7 KiB
C++
122 lines
2.7 KiB
C++
#include <stdio.h>
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#include <string.h>
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#define VM 10000
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#define EM 120000
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#define inf 0x3f3f3f3f
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struct E
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{
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int to,cap,nxt;
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}edge[EM];
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int head[VM],gap[VM],dist[VM],cur[VM],pre[VM];
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int ep;
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void addedge (int cu,int cv,int cw)
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{
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edge[ep].to = cv;
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edge[ep].cap = cw;
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edge[ep].nxt = head[cu];
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head[cu] = ep;
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ep ++;
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edge[ep].to = cu;
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edge[ep].cap = 0;
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edge[ep].nxt = head[cv];
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head[cv] = ep;
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ep ++;
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}
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int min (int a ,int b)
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{
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return a > b ? b : a;
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}
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int sap (int src,int des,int n)
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{
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memset (dist,0,sizeof(dist));
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memset (gap,0,sizeof (dist));
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memcpy (cur,head,sizeof(dist));
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int res = 0;
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int u = pre[src] = src;
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int aug = inf;
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gap[0] = n;
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while (dist[src] < n)
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{
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loop:
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for (int &i = cur[u];i != -1;i = edge[i].nxt)
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{
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int v = edge[i].to;
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if (edge[i].cap && dist[u] == dist[v] + 1)
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{
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aug = min (aug,edge[i].cap);
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pre[v] = u;
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u = v;
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if (v == des)
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{
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res += aug;
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for (u = pre[u];v != src;v = u,u = pre[u])
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{
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edge[cur[u]].cap -= aug;
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edge[cur[u]^1].cap += aug;
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}
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aug = inf; //
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}
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goto loop;
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}
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}
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int mindist = n; //
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for (int i = head[u];i != -1;i = edge[i].nxt)
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{
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int v = edge[i].to;
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if (edge[i].cap && mindist > dist[v])
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{
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cur[u] = i;
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mindist = dist[v];
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}
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}
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if ((--gap[dist[u]]) == 0)
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break;
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dist[u] = mindist + 1;
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gap[dist[u]] ++;
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u = pre[u];
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}
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return res;
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}
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int vis[VM];
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void dfs(int u,int v)
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{
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if(u==v) return ;
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vis[u]=1;
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for(int i=head[u];i!=-1;i=edge[i].nxt)
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if(edge[i].cap>0&&!vis[edge[i].to])
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dfs(edge[i].to,v);
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}
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int main ()
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{
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int n,m,u,v,p;
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int src,des;
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int sum;
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while (scanf("%d %d",&n,&m)!=EOF)
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{
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ep = 0;
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sum=0;
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src = 0;
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des = n + 1;
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memset (head,-1,sizeof(head));
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for(int i=1;i<=n;i++)
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{
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scanf("%d",&p);
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if(p>0)
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{
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addedge(src,i,p);
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sum+=p;
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}
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else
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addedge(i,des,-p);
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}
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for (int i=1; i<=m; i++)
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{
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scanf("%d%d",&u,&v);
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addedge(u,v,inf);
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}
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int max_flow=sap(src,des,n + 2);;
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printf("%d\n",sum-max_flow);
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}
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return 0;
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}
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