Submission #793346

#	Time	Username	Problem	Language	Result	Execution time	Memory
793346		PixelCat	Scales (IOI15_scales)	C++14	100 / 100	10 ms	412 KiB

scales

#ifdef NYAOWO
#include "grader.cpp"
#endif

#include "scales.h"

#include <bits/stdc++.h>
#define For(i, a, b) for(int i = a; i <= b; i++)
#define Forr(i, a, b) for(int i = a; i >= b; i--)
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define sz(x) ((int)x.size())
#define eb emplace_back
using namespace std;
using LL = long long;
using pii = pair<int, int>;

using BS = bitset<720>;

int W[] = {1, 2, 3, 4, 5, 6};
mt19937_64 rng(7456);
uint64_t seed;

// 0 for lightest, 1 for median, 2 for heaviest, 3 for next lightest
vector<vector<int>> perm;
vector<vector<int>> options;
vector<BS> mask[4];

bool match(const vector<int> &ord, const vector<int> &opt, int res) {
    if(opt[0] == 0) {
        bool ok = true;
        For(i, 1, 3) ok = ok && (ord[opt[i]] >= ord[opt[res]]);
        return ok;
    }
    if(opt[0] == 2) {
        bool ok = true;
        For(i, 1, 3) ok = ok && (ord[opt[i]] <= ord[opt[res]]);
        return ok;
    }
    if(opt[0] == 1) {
        int owo = 0;
        For(i, 1, 3) {
            int dif = (ord[opt[i]] - ord[opt[res]]);
            if(dif < 0)  owo |= 1;
            if(dif == 0) owo |= 2;
            if(dif > 0)  owo |= 4;
        }
        return owo == 7;
    }
    if(opt[0] == 3) {
        int o[3] = {opt[1], opt[2], opt[3]};
        sort(o, o + 3, [&](int x, int y){return ord[x] < ord[y];});
        int idx = 0;
        if(ord[opt[4]] > ord[o[2]]) idx = 0;
        else if(ord[opt[4]] > ord[o[1]]) idx = 2;
        else if(ord[opt[4]] > ord[o[0]]) idx = 1;
        idx = o[idx];
        if(idx == opt[1]) idx = 1;
        else if(idx == opt[2]) idx = 2;
        else if(idx == opt[3]) idx = 3;
        return idx == res;
    }
    return false;
}

// how many possibilities remain at most?
int worstmatch(const BS &alive, const int &opt) {
    int mx = 0;
    For(res, 1, 3) {
        mx = max(mx, (int) (alive & mask[res][opt]).count());
    }
    return mx;
}

int best_opt(const BS &alive) {
    int mx = 1000, idx = -1;
    vector<int> all_opt;
    For(i, 0, sz(options) - 1) all_opt.eb(i);
    shuffle(all(all_opt), rng);
    // auto start = clock();
    for(auto &i:all_opt) {
        int k = worstmatch(alive, i);
        if(k < mx) {
            mx = k; idx = i;
        }
    }
    // auto stop = clock();
    // cerr << fixed << setprecision(3);
    // cerr << "elapsed: " << (double)(stop - start) / CLOCKS_PER_SEC << "\n";
    return idx;
}

int make_query(const vector<int> &opt) {
    int x = -1;
    if(opt[0] == 0) {
        x = getLightest(opt[1] + 1, opt[2] + 1, opt[3] + 1);
    } else if(opt[0] == 1) {
        x = getMedian(opt[1] + 1, opt[2] + 1, opt[3] + 1);
    } else if(opt[0] == 2) {
        x = getHeaviest(opt[1] + 1, opt[2] + 1, opt[3] + 1);
    } else if(opt[0] == 3) {
        x = getNextLightest(opt[1] + 1, opt[2] + 1, opt[3] + 1, opt[4] + 1);
    }
    For(i, 1, 3) if(x == opt[i] + 1) return i;
    assert(false);
    return -1;
}

void remove_impossible(BS &alive, const int &opt, int res) {
    alive &= mask[res][opt];
}

// #define TESTING
#ifdef TESTING
int test_all(int lim) {
    map<int, int> cnt;  // {# of queries, count}
    For(i, 0, 719) {
        For(j, 0, 5) W[j] = perm[i][j] + 1;
        _setNewTest(W);
        orderCoins();
        cnt[_numQueries]++;
        if(cnt[7] >= lim) return lim;
    }
    // for(auto &i:cnt) cerr << i.F << ": " << i.S << "\n";
    return cnt[7];
}
uint64_t find_seed() {
    int mn = 120, mni = 48763;
    For(s, 408, 20000) {
        seed = s;
        int k = test_all(mn);
        if(k < mn) {
            mn = k; mni = s;
            cerr << s << " " << k << "\n";
        }
        if(s % 300 == 299) cerr << "progress: " << (s + 1) << "\n";
    }
    return mni;
}
#endif

void init(int T) {
    seed = 3179;

    assert(T < 20);

    int a[6] = {0, 1, 2, 3, 4, 5};
    perm.clear();
    do {
        perm.eb(a, a + 6);
    } while(next_permutation(a, a + 6));
    
    For(i, 0, 5) For(j, i + 1, 5) For(k, j + 1, 5) {
        options.push_back({0, i, j, k});
        options.push_back({1, i, j, k});
        options.push_back({2, i, j, k});
        For(l, 0, 5) {
            if(i == l || j == l || k == l) continue;
            options.push_back({3, i, j, k, l});
        }
    }
    For(r, 1, 3) mask[r].clear();
    for(auto &opt:options) For(r, 1, 3) {
        mask[r].eb();
        mask[r].back().reset();
        For(i, 0, 719) if(match(perm[i], opt, r)) mask[r].back()[i] = 1;
    }

    cerr << sz(perm) << "\n";
    cerr << sz(options) << "\n";

#ifdef TESTING
    // test_all();
    find_seed();
#endif
}

void orderCoins() {
    rng.seed(seed);
    BS alive;
    For(i, 0, 719) alive[i] = 1;

    while(alive.count() > 1) {
        int k = best_opt(alive);
        int r = make_query(options[k]);
        remove_impossible(alive, k, r);
        // cout << sz(alive) << " " << k << " " << r << "\n" << flush;
    }
    
    int pos = -1;
    For(i, 0, 719) if(alive[i]) pos = i;
    vector<int> &ord = perm[pos];
    For(i, 0, 5) W[ord[i]] = i + 1;

#ifndef TESTING
    answer(W);
#endif
}

• Subtask 1: 100 / 100