Submission #1088426

#	Time	Username	Problem	Language	Result	Execution time	Memory
1088426		Pacybwoah	Towns (IOI15_towns)	C++17	48 / 100	16 ms	1032 KiB

towns

#include "towns.h"
#include<vector>
#include<algorithm>
#include<utility>
#include<map>
#include<iostream>
using namespace std;
namespace{
	struct DSU{
		vector<int> dsu, sz;
		DSU(int n){
			dsu.resize(n + 1);
			sz.resize(n + 1);
			for(int i = 0; i <= n; i++) dsu[i] = i, sz[i] = 1;
		}
		int query(int x){
			if(x == dsu[x]) return x;
			dsu[x] = query(dsu[x]);
			return dsu[x];
		}
		void unite(int a, int b){
			a = query(a);
			b = query(b);
			if(a == b) return;
			if(sz[a] < sz[b]) swap(a, b);
			dsu[b] = a;
			sz[a] += sz[b];
		}
	};
}
int hubDistance(int N, int sub) {
	int a = -1, b = -1;
	int maxi = 0, n = N;
	vector<vector<int>> dist(n, vector<int>(n));
	if(sub == 3){
		for(int i = 0; i < n; i++) for(int j = i + 1; j < n; j++) {dist[i][j] = getDistance(i, j); dist[j][i] = dist[i][j];}
		for(int i = 1; i < n; i++){
			int len = dist[0][i];
			if(len > maxi){
				maxi = len;
				a = i;
			}
		}
		vector<int> dista(n), distb(n);
		maxi = 0;
		for(int i = 0; i < n; i++){
			dista[i] = dist[a][i];
			if(dista[i] > maxi){
				maxi = dista[i];
				b = i;
			}
		}
		for(int i = 0; i < n; i++){
			distb[i] = dist[b][i];
		}
		int d = dista[b];
		int ans = 1e9;
		vector<int> dda(n), ddb(n);
		for(int i = 0; i < n; i++){
			int da = (d + dista[i] + distb[i]) / 2 - distb[i], db = (d + dista[i] + distb[i]) / 2 - dista[i];
			ans = min(ans, max(da, db));
			dda[i] = dista[i] - da;
			ddb[i] = distb[i] - db;
		}
		map<int, vector<int>> m;
		for(int i = 0; i < n; i++){
			m[(d + distb[i] + dista[i]) / 2 - distb[i]].push_back(i);
		}
		int sum = 0, maxsz = 0;
			bool flag = 0;
			for(auto &[len, vec]: m){
				if(max(len, d - len) == ans){
					int sz = vec.size();
					DSU dsu(sz);
					for(int i = 0; i < sz; i++){
						for(int j = i + 1; j < sz; j++){
							if(dda[vec[i]] + dda[vec[j]] > dist[vec[i]][vec[j]]){
								dsu.unite(i, j);
							}
						}
					}
					maxsz = 0;
					for(int i = 0; i < sz; i++){
						maxsz = max(maxsz, dsu.sz[i]);
					}
					if(max(maxsz, max(sum, n - sz - sum)) <= n / 2) flag = 1;
				}
				sum += (int)vec.size();
			}
		if(flag) return ans;
		else return -ans;
	}
	for(int i = 1; i < n; i++){
		int len = getDistance(0, i);
		if(len > maxi){
			maxi = len;
			a = i;
		}
	}
	vector<int> dista(n), distb(n);
	maxi = 0;
	for(int i = 0; i < n; i++){
		dista[i] = getDistance(a, i);
		if(dista[i] > maxi){
			maxi = dista[i];
			b = i;
		}
	}
	for(int i = 0; i < n; i++){
		distb[i] = getDistance(b, i);
	}
	int d = dista[b];
	int ans = 1e9;
	for(int i = 0; i < n; i++){
		int da = (d + dista[i] + distb[i]) / 2 - distb[i], db = (d + dista[i] + distb[i]) / 2 - dista[i];
		ans = min(ans, max(da, db));
	}
	if(sub == 4){
		map<int, int> m;
		for(int i = 0; i < n; i++){
			m[(d + distb[i] + dista[i]) / 2 - distb[i]]++;
		}
		int sum = 0;
		bool flag = 0;
		for(auto &[len, val]: m){
			if(max(len, d - len) == ans){
				if(max(val, max(sum, n - sum - val)) <= n / 2) flag = 1;
			}
			sum += val;
		}
		if(flag) return ans;
		else return -ans;
	}
	return ans;
}
// g++ -std=c++17 -Wall -Wextra -fsanitize=undefined -fsanitize=address -Wshadow -o run towns.cpp grader.cpp

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:73:23: warning: conversion from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
   73 |      int sz = vec.size();
      |               ~~~~~~~~^~

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