POJ 2531 Network saboteur

Network saboteur

Time Limit: 2000MS		Memory Limit: 65536K
Total Submissions: 13748		Accepted: 6700

Description

A University Network is composed of N computers. System administrators gathered information on the traffic between nodes, and carefully divided the network into and the subnet Works in order to minimize traffic between parts.
A disgruntled computer science student Vasya, after being expelled from the university, decided to has his revenge. H e hacked into the university network and decided to reassign computers to maximize the traffic between.
Unfortunately, he found, calculating such worst subdivision is one of those problems he, being a student, failed t o solve. So he asks-a more successful CS student, to-help him.
the traffic data is given in the form of Matrix C, where Cij is the amount of data sent between and ith jth (Ci j = Cji, Cii = 0). The goal is to divide the network nodes into the and the disjointed subsets A and B so as to maximize the SUM∑CIJ (I∈A,J∈B). /c0>

Input

The first line of input contains a number of nodes N (2 <= n <= 20). The following n lines, containing n space-separated integers each, represent the traffic matrix C (0 <= Cij <= 10000 ).
Output file must contain a single integer-the maximum traffic between the subnetworks.

Output

Output must contain a single integer-the maximum traffic between the subnetworks.

Sample Input

30 50 3050 0 4030 40 0

Sample Output

90

Source

Northeastern Europe 2002, Far-eastern subregionTranslation:The university network is made up of n computers. The system administrator collects information about the traffic between nodes and carefully divides the network into two subnets to minimize traffic between parts. Vasya, a disgruntled computer science student, decided to retaliate after being expelled from college. He hacked into the university network and decided to reallocate the computer to maximize traffic between the two subnets. Unfortunately, he found that calculating this worst subdivision was one of the problems he had failed to solve as a student. so he asked you, a more successful CS student, to help him. Traffic data is given in the form of Matrix C, where Cij is the amount of data sent between the first and second nodes (Cij = cji,cii = 0). The goal is to divide the network nodes into two unrelated subsets A and B in order to make ΣCIJ (i∈a,j∈b) and maximum. The first line of input contains many nodes N (2 <= n <= 20). The following n rows contain n space-delimited integers representing the flow matrix C (0 <= Cij <= 10000). the output file must contain an integer-maximum traffic between subnets. the output must contain an integer-the maximum traffic between subnets.

#include <cstdio>#include<cstring>#include<iostream>#include<algorithm>using namespacestd;intN,ans;intmp[ -][ -];BOOLflag[ -],a=1, B;voidDfsintPosintNow ) {    if(pos>N) {        if(now>ans) ans=Now ; return ; }    intsum=0; Flag[pos]=A;  for(intI=1; i<pos;i++)        if(flag[i]==b) sum+=Mp[pos][i]; DFS (POS+1, now+sum); Sum=0; flag[pos]=B;  for(intj=1; j<pos;j++)        if(flag[j]==a) sum+=Mp[pos][j]; DFS (POS+1, now+sum);}intMain () { while(SCANF ("%d", &n)! =EOF) {         for(intI=1; i<=n;i++)             for(intj=1; j<=n;j++) scanf ("%d",&Mp[i][j]); Ans=0; DFS (1,0); printf ("%d\n", ans); }  }

POJ 2531 Network saboteur