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C.c
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C.c
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/* LPA 2012/2013 Problem C *
* jdmessias 2009112796 */
#include <stdio.h>
#include <stdlib.h>
short graph[35][35];
short havePrinter[35];
short best;
short actualPrinters;
/* verifica se e solucao, caso seja devolve 1, caso nao seja devolve 0 */
int isSolution(int n)
{
int i, j, sum = 0;
for(i = 0; i < n; i++)
{
sum += havePrinter[i];
for(j = 0; j < n ; j++)
{
if(graph[i][j] == 1)
sum += havePrinter[j];
}
if(sum == 0)
return 0;
sum = 0;
}
return 1;
}
int backtracking(short n, short v, short actualPrinters)
{
int i;
/* rejection test */
if ( actualPrinters >= best)
return 1;
/* base case */
if (isSolution(n) && actualPrinters < best){
best = actualPrinters;
return 1;
}
for(i = v + 1; i < n; i++)
{
havePrinter[i] = 1; /* mark as visited */
backtracking(n, i, actualPrinters + 1); /* recursive step */
havePrinter[i] = 0; /* mark as unvisited */
}
return 0;
}
int main(int argc, const char * argv[])
{
short n, i, j, l;
for(i = 0; i < 35; i++)
{
havePrinter[i] = 0;
for(j = 0; j < 35; j++)
{
graph[i][j] = 0;
}
}
scanf("%hd", &n);
while(scanf("%hd %hd", &j, &l) != EOF)
{
graph[j-1][l-1] = 1;
graph[l-1][j-1] = 1;
}
best = n;
actualPrinters = 0;
backtracking(n, -1, actualPrinters);
printf("%hd\n", best);
return 0;
}