POJ 1129

#include<iostream>
#include<stdio.h>
#include<string>
#define MAXN 60
using namespace std;
int max_clique(int n, int * * mat, int *ret) ;
int main()
{
    //freopen("acm.acm","r",stdin);
    int i;
    int ans;
    int j;
    string s;
    int num;
    int * * _m;
    int * ret;
    while(cin>>num)
    {
        if(num == 0)
            break;
        _m = new int * [num];
        ret = new int[num];
        for(i = 0; i < num; ++ i)
        {
            _m[i] = new int[num];
            memset(_m[i],0,sizeof(int)*num);
        }
    //for(i = 0; i < num; ++ i)
    //        for(j = 0; j < num; ++ j)
    //            cout<<_m[i][j]<<" ";
        for(i = 0; i < num; ++ i)
        {
            cin>>s;
            if(s.length() == 2)
                continue;
            else
            {
                for(j = 2; j < s.length(); ++ j)
                {
                    _m[s[0] - 'A'][s[j] - 'A'] = 1;
                }
            }
        }
    ans = max_clique(num,_m,ret);
    cout<<ans;
    if(ans == 1)
        cout<<" channel needed."<<endl;
    else
        cout<<" channels needed."<<endl;
    delete [] _m;
    delete ret;
    }
}


void clique(int n, int* u, int * * mat, int size, int& max, int& bb, int * res, int* rr, int* c) {
    int i, j, vn, v[MAXN];
    if (n) {
        if (size + c[u[0]] <= max) return;
        for (i = 0; i < n + size - max && i < n; ++ i) {
            for (j = i + 1, vn = 0; j < n; ++ j)
                if (mat[u[i]][u[j]])
                    v[vn ++] = u[j];
            rr[size] = u[i];
            clique(vn, v, mat, size + 1, max, bb, res, rr, c);
            if (bb) return;
        }
    } else if (size > max) {
        max = size;
        for (i = 0; i < size; ++ i)
            res[i] = rr[i];
        bb = 1;
    }
}

int max_clique(int n, int * *mat, int * ret) {
    int max = 0, bb, c[MAXN], i, j;
    int vn, v[MAXN], rr[MAXN];
    for (c[i = n - 1] = 0; i >= 0; -- i) {
        for (vn = 0, j = i + 1; j < n; ++ j)
            if (mat[i][j])
                v[vn ++] = j;
        bb = 0;
        rr[0] = i;
        clique(vn, v, mat, 1, max, bb, ret, rr, c);
        c[i] = max;
    }
    return max;
}

 

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