Codeforces 510E Fox and Dinner

Codeforces 510E

Prime number hit Table + Max stream + Max stream print path

Note a_{i (2≤ ai ≤10^{4). Then all primes in the title must be an odd number and an even number. So all the tables are even rings.}}

Connect all the even points to the super source point, and the singularity points to the super sinks, with a capacity of 2. The edge of 1 is built between all the odd points and the odd points, and if full flow, the condition can be satisfied

Draw a picture to know that such a map is the correct →_→, how can you think of this point? Weak and not made

#include <cstdio> #include <cstring> #include <algorithm> #include <cmath> #include <queue >using namespace Std;const int maxn=208;const int maxm=20008;const int inf=0x7f7f7f7f;int Sb[maxn],sx[maxn];bool pri[ Maxm];void shit () {memset (pri,false,sizeof (PRI));p ri[2]=true;int i,j,x;for (i=3;i<=20000;i++) {x=sqrt (i); for (j=2 ; j<=x;j++) if (i%j==0) break;if (j>x) pri[i]=true;}} struct Fuck{int u,v,cap,next;} Edge[maxm];int tol;int head[maxn];void init () {Tol=0;memset (head,-1,sizeof (Head));} void Addedge (int u,int v,int W) {edge[tol].u=u;edge[tol].v=v;edge[tol].next=head[u];edge[tol].cap=w;head[u]=tol++; edge[tol].v=u;edge[tol].u=v;edge[tol].cap=0;edge[tol].next=head[v];head[v]=tol++;} BOOL Vis[maxn];int dep[maxn],gap[maxn];void BFS (int sour,int sink) {Queue<int>q;memset (vis,false,sizeof (VIS)); memset (dep,-1,sizeof (DEP)); Memset (Gap,0,sizeof (GAP)); Q.push (sink);d Ep[sink]=0;gap[0]=1;vis[sink]=true;int u,v,i ; while (!q.empty ()) {U=q.front (); Q.pop (); for (I=head[u];i!=-1;i=edge[i].next{v=edge[i].v;if (!vis[v]&&edge[i].cap==0) {Vis[v]=true;dep[v]=dep[u]+1;q.push (v); gap[dep[v]]++;}}}} int cur[maxn],s[maxm];int last;int SAP (int sour,int sink) {BFS (sour,sink); int max_flow=0,i,u;for (i=0;i<=last;i++) Cur[i]=head[i];int Top=0;u=sour;while (dep[sour]<last) {if (u==sink) {int temp=inf,inser;for (i=0;i<top;i++) {if (edge[s[i]].cap<temp) {temp=edge[s[i]].cap;inser=i;}} for (i=0;i<top;i++) {edge[s[i]].cap-=temp;edge[s[i]^1].cap+=temp;} MAX_FLOW+=TEMP;TOP=INSER;U=EDGE[S[TOP]].U;} if (u!=sink&&gap[dep[u]-1]==0) break;for (I=cur[u];i!=-1;i=edge[i].next) if (edge[i].cap>0&&dep[ u]==dep[edge[i].v]+1) break;if (i!=-1) {cur[u]=i; S[TOP++]=I;U=EDGE[I].V;} Else{int mi=last;for (I=head[u];i!=-1;i=edge[i].next) {if (edge[i].cap==0) continue;if (mi>dep[edge[i].v]) {MI=DEP [Edge[i].v];cur[u]=i;}} --gap[dep[u]];d ep[u]=mi+1;++gap[dep[u]];if (u!=sour) u=edge[s[--top]].u;} return max_flow;} int zhan[maxn];int lin[maxn];int sum;int li[maxn];int dian[maxn];int w[maxn];void dfs (int u,int idx{vis[u]=true;sum++;int i;if (U&LT;=IDX) {for (I=head[u];i!=-1;i=edge[i].next) if (edge[i].cap==0&&edge[i].v !=0&AMP;&AMP;!VIS[EDGE[I].V]) {Lin[u]=edge[i].v;dfs (EDGE[I].V,IDX);}} Else{for (I=head[u];i!=-1;i=edge[i].next) if (edge[i].cap>0&&edge[i].v!=last-1&&!vis[edge[i].v ]) {Lin[u]=edge[i].v;dfs (EDGE[I].V,IDX);}}} int main () {int i,j,n,m,x;shit (); while (scanf ("%d", &n) ==1) {int idx,idb;idx=idb=0;init (); for (i=1;i<=n;i++) { scanf ("%d", &x); if (x&1) {sb[++idb]=x;dian[idb]=i;} Else{sx[++idx]=x;w[idx]=i;}} for (i=1;i<=idx;i++) for (j=1;j<=idb;j++) {if (Pri[sx[i]+sb[j]) Addedge (i,j+idx,1);} int sour,sink;sour=0;sink=n+1;for (i=1;i<=idx;i++) Addedge (sour,i,2); for (i=1;i<=idb;i++) Addedge (I+idx,sink, 2); Last=n+2;int Ans=sap (Sour,sink); if (ans!=n) printf ("impossible\n"); else{ans=0; int Id=0;memset (Vis,false,sizeof ( VIS); Memset (Lin,-1,sizeof (Lin)); for (i=1;i<=idx;i++) {if (!vis[i]) {Sum=0;dfs (I,IDX); li[id]=i;zhan[id++]=sum;}} printf ("%d\n", id); for (i=0;i<id;i++) {printf ("%d", enAn[i]), int pa=li[i];while (pa!=-1) {if (PA&LT;=IDX) printf ("%d", W[pa]), elseprintf ("%d", Dian[pa-idx]);p A=LIN[PA];} printf ("\ n");}}} return 0;}

Codeforces 510E Fox and Dinner