Submission #640509

#	Time	Username	Problem	Language	Result	Execution time	Memory
640509		piOOE	Towns (IOI15_towns)	C++17	48 / 100	257 ms	9536 KiB

towns

#include <bits/stdc++.h>
#include "towns.h"

using namespace std;

int hubDistance(int n, int sub) {
    map<pair<int, int>, int> mp;
    auto mygetDistance = [&](int x, int y) {
        if (mp.count({x, y})) {
            return mp[{x, y}];
        } else {
            return mp[{x, y}] = mp[{y, x}] = getDistance(x, y);
        }
    };
    if (sub <= 2) {
        vector<int> dist(n);
        for (int i = 0; i < n; ++i) {
            dist[i] = mygetDistance(i, 0);
        }
        int v = max_element(dist.begin(), dist.end()) - dist.begin();
        for (int i = 0; i < n; ++i) {
            dist[i] = mygetDistance(i, v);
        }
        int u = max_element(dist.begin(), dist.end()) - dist.begin();
        vector<int> dist2(n);
        for (int i = 0; i < n; ++i) {
            dist2[i] = mygetDistance(i, u);
        }
        int ans = numeric_limits<int>::max();
        for (int i = 0; i < n; ++i) {
            int e = dist[i] + dist2[i] - dist[u] >> 1;
            ans = min(ans, max(dist[i] - e, dist2[i] - e));
        }
        return ans;
    } else {

        if (sub == 4) {

            vector<int> dist(n), e(n);
            for (int i = 0; i < n; ++i) {
                dist[i] = mygetDistance(i, 0);
            }

            int a = max_element(dist.begin(), dist.end()) - dist.begin();
            for (int i = 0; i < n; ++i) {
                dist[i] = mygetDistance(i, a);
            }

            int b = max_element(dist.begin(), dist.end()) - dist.begin();
            vector<int> dist2(n);
            for (int i = 0; i < n; ++i) {
                dist2[i] = mygetDistance(i, b);
            }

            int ans = numeric_limits<int>::max();

            vector<int> mega;
            for (int i = 0; i < n; ++i) {
                if (i != b && i != a) {
                    e[i] = (dist[i] + dist2[i] - dist[b]) >> 1;
                    mega.push_back(dist[i] - e[i]);
                    ans = min(ans, max(mega.back(), dist[b] - mega.back()));
                }
            }

            sort(mega.begin(), mega.end());
            mega.resize(unique(mega.begin(), mega.end()) - mega.begin());
            const int m = mega.size();

            vector<int> adj(n), cnt(m);
            vector<vector<int>> kids(m);

            for (int i = 0; i < n; ++i) {
                if (i != b && i != a) {
                    adj[i] = lower_bound(mega.begin(), mega.end(), dist[i] - e[i]) - mega.begin();
                    kids[adj[i]].push_back(i);
                    ++cnt[adj[i]];
                }
            }
            for (int i = 0; i < m; ++i) {
                if (max(mega[i], dist[b] - mega[i]) == ans) {
                    int L = 1, R = 1;
                    for (int j = 0; j < i; ++j) {
                        L += cnt[j];
                    }
                    for (int j = i + 1; j < m; ++j) {
                        R += cnt[j];
                    }
                    if (max({L, R, cnt[i]}) <= n / 2) {
                        return ans;
                    }
                }
            }
            return -ans;
        } else {
            vector dist(n, vector<int>(n));
            for (int i = 0; i < n; ++i) {
                for (int j = i + 1; j < n; ++j) {
                    dist[i][j] = dist[j][i] = getDistance(i, j);
                }
            }
            vector mp(n, vector<map<int, int>>(n));
            vector<int> verts = {228};
            vector<vector<pair<int, int>>> kids = {{}};

            for (int i = 0; i < n; ++i) {
                for (int j = i + 1; j < n; ++j) {
                    for (int k = j + 1; k < n; ++k) {
                        int a = dist[i][j];
                        int b = dist[j][k];
                        int c = dist[k][i];
                        int x = (a - b + c) / 2;
                        int y = a - x;
                        int z = c - x;
                        int s = max({mp[i][j][x], mp[j][k][y], mp[i][k][x]});
                        if (s == 0) {
                            s = verts.size();
                            verts.push_back(0);
                            kids.emplace_back();
                        }
                        kids[s].emplace_back(x, i);
                        kids[s].emplace_back(y, j);
                        kids[s].emplace_back(z, k);
                        mp[i][j][x] = mp[j][k][y] = mp[i][k][x] = s;
                        verts[s] = max({verts[s], x, y, z});
                    }
                }
            }
            int ans = *min_element(verts.begin() + 1, verts.end());
            for (int r = 1; r < kids.size(); ++r) {
                if (verts[r] == ans) {
                    vector<int> p(n), sz(n, 1);
                    iota(p.begin(), p.end(), 0);
                    auto get = [&](int x) {
                        while (x != p[x]) x = p[x] = p[p[x]];
                        return x;
                    };
                    auto unite = [&](int x, int y) {
                        x = get(x), y = get(y);
                        if (x != y) {
                            p[y] = x;
                            sz[x] += sz[y];
                        }
                    };
                    sort(kids[r].begin(), kids[r].end());
                    kids[r].resize(unique(kids[r].begin(), kids[r].end()) - kids[r].begin());
                    assert(kids[r].size() == n);
                    for (int i = 0; i < n; ++i) {
                        for (int j = 0; j < n; ++j) {
                            if (i != j) {
                                auto [wx, x] = kids[r][i];
                                auto [wy, y] = kids[r][j];
                                assert(wx + wy >= dist[x][y]);
                                if (wx + wy != dist[x][y]) {
                                    unite(x, y);
                                }
                            }
                        }
                    }
                    if (*max_element(sz.begin(), sz.end()) <= n / 2) {
                        return ans;
                    }
                }
            }
            return -ans;
        }
    }
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:20:55: warning: conversion from '__gnu_cxx::__normal_iterator<int*, std::vector<int> >::difference_type' {aka 'long int'} to 'int' may change value [-Wconversion]
   20 |         int v = max_element(dist.begin(), dist.end()) - dist.begin();
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
towns.cpp:24:55: warning: conversion from '__gnu_cxx::__normal_iterator<int*, std::vector<int> >::difference_type' {aka 'long int'} to 'int' may change value [-Wconversion]
   24 |         int u = max_element(dist.begin(), dist.end()) - dist.begin();
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
towns.cpp:31:40: warning: suggest parentheses around '-' inside '>>' [-Wparentheses]
   31 |             int e = dist[i] + dist2[i] - dist[u] >> 1;
towns.cpp:44:59: warning: conversion from '__gnu_cxx::__normal_iterator<int*, std::vector<int> >::difference_type' {aka 'long int'} to 'int' may change value [-Wconversion]
   44 |             int a = max_element(dist.begin(), dist.end()) - dist.begin();
      |                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
towns.cpp:49:59: warning: conversion from '__gnu_cxx::__normal_iterator<int*, std::vector<int> >::difference_type' {aka 'long int'} to 'int' may change value [-Wconversion]
   49 |             int b = max_element(dist.begin(), dist.end()) - dist.begin();
      |                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
towns.cpp:68:36: warning: conversion from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
   68 |             const int m = mega.size();
      |                           ~~~~~~~~~^~
towns.cpp:75:84: warning: conversion from '__gnu_cxx::__normal_iterator<int*, std::vector<int> >::difference_type' {aka 'long int'} to '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'} may change value [-Wconversion]
   75 |                     adj[i] = lower_bound(mega.begin(), mega.end(), dist[i] - e[i]) - mega.begin();
      |                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
towns.cpp:102:20: warning: declaration of 'mp' shadows a previous local [-Wshadow]
  102 |             vector mp(n, vector<map<int, int>>(n));
      |                    ^~
towns.cpp:7:30: note: shadowed declaration is here
    7 |     map<pair<int, int>, int> mp;
      |                              ^~
towns.cpp:117:43: warning: conversion from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
  117 |                             s = verts.size();
      |                                 ~~~~~~~~~~^~
towns.cpp:130:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<std::pair<int, int> > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  130 |             for (int r = 1; r < kids.size(); ++r) {
      |                             ~~^~~~~~~~~~~~~
In file included from /usr/include/c++/10/cassert:44,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:33,
                 from towns.cpp:1:
towns.cpp:147:43: warning: comparison of integer expressions of different signedness: 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  147 |                     assert(kids[r].size() == n);
      |                            ~~~~~~~~~~~~~~~^~~~

• Subtask 1: 13 / 13
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 10 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 39