POJ 2531 Network saboteur (DFS)

Network saboteur

Time Limit: 2000MS		Memory Limit: 65536K
Total Submissions: 9364		Accepted: 4417

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. He 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 the those problems he, being a student, failed to so Lve. 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 (nodes = 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).

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

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Test instructions: Divides a connected set into two disconnected sets, seeking the maximum amount of information exchanged between the two sets.

Each point (computer) can be divided into a set or B by two choices.

Each time a point is sorted, the amount of information exchanged between it and another set is immediately calculated.

#include <stdio.h> #include <queue> #include <map> #include <string> #include <string.h> using namespace std; #define N 25const int inf=0x1f1f1f1f;int g[n][n];int ans,n;bool f[n];void dfs (int u,int sum) {    if (U >=n)    {        Ans=max (ans,sum);        return;    }    int i,tmp=0;    F[u]=false;         Divide the point u into set a    for (i=0;i<u;i++)   //Seek point U and set B to exchange the amount of information        if (f[i]==true)            tmp+=g[u][i];    DFS (U+1,SUM+TMP);    F[u]=true;          Divide the point u into set B for    (i=tmp=0;i<u;i++)//Seek points U and set a exchange amount of information        if (f[i]==false)        tmp+=g[u][i];    DFS (U+1,SUM+TMP);} int main () {    int i,j;    while (scanf ("%d", &n)!=-1)    {        for (i=0; i<n; i++)            for (j=0; j<n; j + +)                scanf ("%d", &g[ I][J]);        ans=0;        DFS (0,0);        printf ("%d\n", ans);    }    return 0;}

Poj 2531 Network saboteur (Dfs)