Submission #241718

#	Time	Username	Problem	Language	Result	Execution time	Memory
241718		godwind	Shortcut (IOI16_shortcut)	C++14	23 / 100	2094 ms	4988 KiB

shortcut

#include "shortcut.h"
#include <iostream>
#include <vector>
#include <algorithm>
#include <random>
#include <set>
#include <map>
#include <queue>
#include <cstring>
#include <cmath>
#include <bitset>
#include <iomanip>
#include <functional>

using namespace std;

const int N = 1000;
const long long INF = 1e18 + 228;

vector< pair<int, int> > g[N];

void AddEdge(int u, int v, int w) {
	g[u].emplace_back( v, w );
	g[v].emplace_back( u, w );
}

long long dist[N][N];

void dfs(int v, int st, long long DST = 0, int par = -1) {
	dist[v][st] = DST;
	for (auto go : g[v]) {
		int to = go.first;
		int w = go.second;
		if (to == par) continue;
		dfs(to, st, DST + w, v);
	}
}

mt19937 rnd(rand());

long long find_shortcut(int n, vector<int> l, vector<int> d, int c)
{
	for (int i = 0; i < n - 1; ++i) {
		AddEdge(i, i + 1, l[i]);
	}
	for (int i = 0; i < n; ++i) {
		AddEdge(i, n + i, d[i]);
	}
	int V = 2 * n - 1;
	for (int i = 0; i < V; ++i) {
		dfs(i, i);
	}
	vector< pair<int, int> > ord;
	for (int i = 0; i < n; ++i) {
		for (int j = i + 1; j < n; ++j) {
			ord.emplace_back( i , j );
		}
	}
	shuffle( ord.begin(), ord.end(), rnd );
	vector< pair<int, int> > ord2;
	for (int i = 0; i < n; ++i) {
		for (int j = i + 1; j < n; ++j) {
			ord2.emplace_back( i, j );
		}
	}
	sort( ord2.begin(), ord2.end(), [&] (pair<int, int> A, pair<int, int> B) {
		return dist[A.first][A.second] > dist[B.first][B.second];
	});
	long long best = INF;
	for (auto P : ord) {
		int A = P.first, B = P.second;
		long long cur_dia = 0;
		for (auto _p : ord2) {
			int i = _p.first, j = _p.second;
			long long cur = min({dist[i][j], dist[i][A] + c + dist[j][B], dist[i][B] + c + dist[j][A]});
			cur = cur + d[i] + d[j];
			cur_dia = max(cur_dia, cur);
			if (cur_dia >= best) {
				break;
			}
		}
		if (cur_dia < best) {
			best = cur_dia;
		}
	}
    return best;
}

• Subtask 1: 9 / 9
• Subtask 2: 14 / 14
• Subtask 3: 0 / 8
• Subtask 4: 0 / 7
• Subtask 5: 0 / 33
• Subtask 6: 0 / 22
• Subtask 7: 0 / 4
• Subtask 8: 0 / 3