Cod sursa(job #404283)

Utilizator TabaraTabara Mihai Tabara Data 25 februarie 2010 23:43:22
Problema Parantezare optima de matrici Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 0.9 kb
/*
@ Mihai Tabara, 2010
Method: PD
O(n^3) - time
O(N^2) - memory
*/

#include <fstream>
#include <climits>
#include <cstdio>
#include <cstdlib>
using namespace std;

const char* in = "podm.in";
const char* out = "podm.out";
const int NMAX = 505;
const long long INF = LLONG_MAX; 

long long M[NMAX][NMAX];
long long P[NMAX];
int N;

long long Mat ( int i, int j )
{
	long long Q;
	int k;
	if ( M[i][j] < INF )
		return M[i][j];
	if ( i == j )
		M[i][j] = 0;
	else
	{
		for ( k = i; k <= j-1; ++k )
		{
			Q = Mat ( i, k ) + Mat ( k+1, j ) + P[i-1] * P[k] * P[j];
			if ( Q < M[i][j] ) 
				M[i][j] = Q;
		}
	}
	return M[i][j];
}

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

	scanf ( "%d", &N );
	
	int i, j;
	for ( i = 0; i <= N; scanf ( "%lld", P+i++ ) );
	
	for ( i = 1; i <= N; ++i )
		for ( j = 1; j <= N; ++j )
			M[i][j] = INF;
	
	printf ( "%lld\n", Mat( 1, N ) );
	return 0;
}