Cod sursa(job #75967)

Utilizator DastasIonescu Vlad Dastas Data 6 august 2007 21:19:46
Problema Oite Scor 10
Compilator cpp Status done
Runda Arhiva de probleme Marime 1.09 kb
#include <cstdio>
#include <vector>

using namespace std;

#define maxn 1024
#define maxp 666013

FILE *in = fopen("oite.in", "r"), *out = fopen("oite.out", "w");

struct hash
{
    int i, j;
};

int n;
int L;
int a[maxn];
//hash *h[maxp] = {NULL};
vector<hash> h[maxn];

void hadd(int p, int q)
{
    int t = (a[p] + a[q]) % maxp;
    hash tt;
    tt.i = p;
    tt.j = q;
    h[t].push_back(tt);
}

int hget(int p, int q)
{
    int s = 0;

    if ( L - (a[p] + a[q]) < 0 )
        return 0;

    int t = (L - (a[p] + a[q])) % maxp;

    for ( vector<hash>::iterator i = h[t].begin(); i != h[t].end(); ++i )
        if ( (*i).i > q  )
            ++s;

    return s;
}

int main()
{
    fscanf(in, "%d %d", &n, &L);

    for ( int i = 0; i < n; ++i )
        fscanf(in, "%d", &a[i]);

    for ( int i = 0; i < n; ++i )
        for ( int j = i+1; j < n; ++j )
            hadd(i, j);

    int cnt = 0;
    for ( int i = 0; i < n; ++i )
        for ( int j = i+1; j < n; ++j )
            cnt += hget(i, j);

    fprintf(out, "%d\n", cnt);

	return 0;
}