CSU 1552:friends graph theory match + super large prime number judgment

1552:friends time limit:3 Sec Memory limit:256 MB
submit:163 solved:34
[Submit] [Status] [Web Board] Description

On an alien planet, every extraterrestrial are born with a number. If the sum of the numbers is a prime number and then both extraterrestrials can be friends. But every extraterrestrial can only have at the most one friend. You is given all number of the extraterrestrials and please determining the maximum number of friend pair.

Input

There is several test cases.
Each test start with positive integers n (1≤n≤100), which means there is n extraterrestrials on the alien planet.
The following N lines, each line contains a positive integer pi (2≤pi≤10^18), indicate the i-th extraterrestrial is Bor N with pi number.
The input would finish with the end of file.

Output

For each case, your program would output maximum number of friend pair.

Sample Input

322342538

Sample Output

12

1#include <cstdio>2#include <cstring>3#include <cmath>4#include <algorithm>5#include <string>6#include <vector>7#include <Set>8#include <map>9#include <stack>Ten#include <queue> One#include <sstream> A#include <iomanip> -#include <ctime> - using namespacestd; thetypedefLong LongLL; - Const intinf=0x4fffffff; - Const intexp=1e-5; - Const intms= the; +  - intVis[ms]; + intEdge[ms][ms]; A  at intLin[ms]; - LL A[ms]; - intN; -  -  - // in LL MIN; - ll Mult_mod (ll a,ll b,ll N) to { +LL s=0; -      while(b) the     { *         if(b&1) s= (s+a)%N; $A= (a+a)%N;Panax Notoginsengb>>=1; -     } the     returns; + } A  the ll Pow_mod (ll a,ll b,ll N) + { -LL s=1; $      while(b) $     { -         if(b&1) s=Mult_mod (s,a,n); -A=Mult_mod (a,a,n); theb>>=1; -     }Wuyi     returns; the } -  Wu BOOLPrime (LL N) - { AboutLL u=n-1, pre,x; $     inti,j,k=0; -     if(n==2|| n==3|| n==5|| n==7|| n== One)return 1; -     if(n==1|| (! (n%2))|| (! (n%3))|| (! (n%5))|| (! (n%7))|| (! (n% One)))return 0; -      for(;! (u&1); k++,u>>=1); ASrand (LL) Time (0)); +      for(i=0;i<5; i++) the     { -X=rand ()% (n2)+2; $x=Pow_mod (x,u,n); thePre=x; the          for(j=0; j<k;j++) the         { thex=Mult_mod (x,x,n); -             if(x==1&&pre!=1&&pre!= (n1)) in                 return 0; thePre=x; the         } About         if(x!=1)return false; the     } the     return true; the } +  - BOOLDfsintX//Dfs Augmentation Road the {Bayi        for(intI=1; i<=n;i++) the       { the             if(edge[x][i]&&!Vis[i]) -             { -vis[i]=1; the                   if(lin[i]==-1|| DFS (Lin[i]))//I have no matching or matching can get the augmented path the                   { thelin[i]=x; the                         return true; -                   } the             } the       } the       return false;94 } the  the intMain () the {98        while(SCANF ("%d", &n)! =EOF) About       { -Memset (Edge,0,sizeof(Edge));101              for(intI=1; i<=n;i++)102scanf"%lld",&a[i]);103              for(intI=1; i<=n;i++)104                    for(intj=i+1; j<=n;j++) the                         if(Prime (a[i]+A[j]))106edge[i][j]=edge[j][i]=1;107             intcn1=0;108memset (lin,-1,sizeof(Lin));109              for(intI=1; i<=n;i++) the             {111memset (Vis,0,sizeof(Vis)); the                   if(Dfs (i))113ans++; the             } theprintf"%d\n", ans/2); the       }117       return 0;118}

CSU 1552:friends graph theory match + super large prime number judgment