제출 #640502

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
640502		piOOE	Towns (IOI15_towns)	C++17	25 / 100	19 ms	468 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 {
        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();
                assert(mega[adj[i]] + e[i] == dist[i]);
                kids[adj[i]].push_back(i);
                ++cnt[adj[i]];
            }
        }

        int vis = 0;
        assert(*min_element(cnt.begin(), cnt.end()));
        for (int i = 0; i < m; ++i) {
            if (max(mega[i], dist[b] - mega[i]) == ans) {
                ++vis;
                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;
                }
            }
        }
        assert(vis);
        return ans;
    }
}

컴파일 시 표준 에러 (stderr) 메시지

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:41:55: warning: conversion from '__gnu_cxx::__normal_iterator<int*, std::vector<int> >::difference_type' {aka 'long int'} to 'int' may change value [-Wconversion]
   41 |         int a = max_element(dist.begin(), dist.end()) - dist.begin();
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
towns.cpp:46:55: warning: conversion from '__gnu_cxx::__normal_iterator<int*, std::vector<int> >::difference_type' {aka 'long int'} to 'int' may change value [-Wconversion]
   46 |         int b = max_element(dist.begin(), dist.end()) - dist.begin();
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
towns.cpp:65:32: warning: conversion from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
   65 |         const int m = mega.size();
      |                       ~~~~~~~~~^~
towns.cpp:72:80: 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]
   72 |                 adj[i] = lower_bound(mega.begin(), mega.end(), dist[i] - e[i]) - mega.begin();
      |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~

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