Cod sursa(job #8064)

Utilizator love_for_uSpancioc Riana love_for_u Data 23 ianuarie 2007 19:42:02
Problema Triplete Scor 0
Compilator cpp Status done
Runda Arhiva de probleme Marime 1.26 kb

#include <stdio.h>
#define NMAX 4096
#define MMAX 66000
#define B 32
#define P 5

struct per { int x, y; } V[MMAX];

char Nr[1 << (B/2) ];
int A[NMAX][ NMAX/B + 1];
int i, j, N, M, a, b, cfg;
long long rez;

inline void set(int cnf,int x)
{
   A[cnf][x>>P] |= 1 << (x & (B-1));
}

void prep()
{
     int i;

     Nr[0] = 0;

     for (i = 0; i < 1 << (B/2); i++)
       Nr[i] = Nr[i >> 1] + (i&1);
}

int main()
{
     freopen("triplete.in","r",stdin);
     freopen("triplete.out","w",stdout);

     scanf("%d %d", &N, &M);

     if (N == 1) { printf("0\n"); return 0; }
     if (N == 2) { printf("0\n"); return 0; }
     if (N == 3 && M != 3) { printf("0\n"); return 0;}

     rez = 0;

     for (i = 1; i <= M; i++)
     {
          scanf("%d %d", &a, &b);

          V[i].x = a;
          V[i].y = b;

          set(a, b);
          set(b, a);
     }

     prep();

     for (i = 1; i <= M; i++)
     {
          a = V[i].x;
          b = V[i].y;

          for (j = 0; j <= N/B; j++)
          {
               cfg = A[a][j] & A[b][j];

               if (cfg > 1 << (B/2)) rez += Nr[cfg >> 1] + (cfg&1);
               else rez += Nr[cfg];
          }
     }

     printf("%lld\n", rez/3);

     return 0;
}