117 lines
2.8 KiB
C++
117 lines
2.8 KiB
C++
#include<cstdio>
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#include<cstring>
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using namespace std;
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const int inf=1<<30;
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const int nMax=10105;
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const int mMax=3000005;
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struct Node
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{
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int c,u,v,next;
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void insert(int nu,int nv,int nc,int nnext)
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{
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u=nu;
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v=nv;
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c=nc;
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next=nnext;
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}
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}edge[mMax];
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int ne,head[nMax];
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int cur[nMax],ps[nMax],dep[nMax];
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void addedge(int u,int v,int w)
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{
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edge[ne].insert(u,v,w,head[u]);
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head[u]=ne++;
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edge[ne].insert(v,u,0,head[v]);
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head[v]=ne++;
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}
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int dinic(int s, int t){
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int tr, res = 0;
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int i, j, k, f, r, top;
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while(1){
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memset(dep, -1, sizeof(dep));
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for(f = dep[ps[0]=s] = 0, r = 1; f != r;)
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{
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for(i = ps[f ++], j = head[i]; j; j = edge[j].next)
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{
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if(edge[j].c && dep[k=edge[j].v] == -1)
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{
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dep[k] = dep[i] + 1;
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ps[r ++] = k;
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if(k == t)
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{
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f = r; break;
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}
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}
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}
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}
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if(dep[t] == -1) break;
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memcpy(cur, head, sizeof(cur));
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i = s, top = 0;
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while(1)
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{
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if(i == t)
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{
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for(tr =inf, k = 0; k < top; k ++)
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{
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if(edge[ps[k]].c < tr)
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{
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tr = edge[ps[f=k]].c;
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}
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}
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for(k = 0; k < top; k ++)
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{
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edge[ps[k]].c -= tr;
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edge[ps[k]^1].c += tr;
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}
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i = edge[ps[top=f]].u;
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res += tr;
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}
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for(j = cur[i]; cur[i]; j = cur[i] =edge[cur[i]].next)
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{
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if(edge[j].c && dep[i]+1 == dep[edge[j].v])
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{
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break;
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}
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}
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if(cur[i])
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{
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ps[top ++] = cur[i];
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i = edge[cur[i]].v;
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}
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else
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{
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if(top == 0)
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{
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break;
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}
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dep[i] = -1;
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i = edge[ps[-- top]].u;
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}
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}
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}
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return res;
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}
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int main()
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{
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int i,j,a,b,s,t,m,n;
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while(~scanf("%d%d%d%d",&n,&m,&s,&t))
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{
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ne=2;
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memset(head,0,sizeof(head));
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for(i=1;i<=n;i++)
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{
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scanf("%d",&a);
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addedge(i,i+n,a);
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}
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for(i=1;i<=m;i++)
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{
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scanf("%d%d",&a,&b);
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addedge(a+n,b,inf);
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addedge(b+n,a,inf);
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}
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int res=dinic(s,t+n);
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printf("%d\n",res);
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}
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return 0;
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}
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