https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=1949

11008 - Antimatter Ray Clearcutting.cpp

#include <bits/stdc++.h>

#define ll long long
#define sz(v) ((int) ((v).size()))
#define clr(v, d) memset(v, d, sizeof(v))
#define lp(i, n) for(int i = 0; i < (int)(n); ++i)
#define rep(i, v) for(int i = 0; i < sz(v); ++i)

using namespace std;

int getBit(int num, int indx) {
    return ((num>>indx) & 1) == 1;
}

int setBit1(int num, int indx) {
    return num | (1<<indx);
}

int setBit0(int num, int indx) {
    return num & ~(1<<indx);
}

int cntBits(int num) {
    int ret = 0;
    while(num) {
        if(num%2) {
            ret++;

        }
        num/=2;
    }
    return ret;
}

const int MAX = 10;
const int OO = 1e9;

int n, m;
string s;
int cache[1<<16];
int X[20], Y[20];
int preprocessed[20][20];

int minRay(int mask) {
    //cout << "DEBUG :" << " " << m << endl;

    if(n-cntBits(mask) >= m) {
        return 0;
    }

    int &ret = cache[mask];
    if(ret != -1)
        return ret;
    ret = OO;

    vector<int> ones;
    lp(i, n) {
        if(getBit(mask, i))
            ones.push_back(i);
    }

    for(int i = 0; i < sz(ones); i++) {

        for(int j = i+1; j < sz(ones); j++) {
            int tmpm = mask & preprocessed[ ones[i] ][ ones[j] ];
            //cout << "DEBUG HERE: " << tmpm << endl;
            ret = min(ret, 1+minRay(tmpm));
            //cout << "HRRRRRRRRRRRRRRRRRRRRRR\n";
        }
    }
    if(ret == OO)
        return ret = 1;

    return ret;
}

void preprocess() {
    lp(i, n) {
        for(int j = 0; j < n; j++) {
            if(i != j) {
                int tmpm = (1<<n)-1;
                tmpm = setBit0(tmpm, i);
                tmpm = setBit0(tmpm, j);
                for(int k = 0; k < n ; k++) {
                    if(i != k && j != k) {

                        int x1 = X[j] - X[i];
                        int y1 = Y[j] - Y[i];
                        int x2 = X[k] - X[i];
                        int y2 = Y[k] - Y[i];
                        if(x1*y2 - x2*y1 == 0)
                            tmpm = setBit0(tmpm, k);
                    }
                }
                preprocessed[i][j] = tmpm;
            }
        }
    }
}
int main() {
    int t;
    cin>>t;
    lp(i, t) {
        clr(cache, -1);
        cin>>n>>m;
        lp(j, n) {
            cin>>X[j]>>Y[j];
        }
        preprocess();
        int mask = (1<<n)-1;
        cout << "Case #" << i+1 << ":\n" << minRay(mask) << "\n";
        if(i != t-1)
            cout << endl;
    }
    return 0;
}