Submission #405275

#	Time	Username	Problem	Language	Result	Execution time	Memory
405275		dxz05	Simurgh (IOI17_simurgh)	C++14	13 / 100	465 ms	332 KiB

simurgh

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

using namespace std;

const int MAXN = 5e5 + 3e2;
typedef long long ll;

vector<pair<int, int>> edges;

int par[MAXN];
int findset(int x){
    if (x == par[x]) return x;
    return par[x] = findset(par[x]);
}

bool unite(int x, int y){
    x = findset(x);
    y = findset(y);
    if (x == y) return false;
    if (rand() % 2) swap(x, y);
    par[x] = y;
    return true;
}

int n;
bool check(vector<int> &r){
    if (r.size() != n - 1) return false;
    for (int i = 0; i < n; i++) par[i] = i;
    int cnt = 0;
    for (int i : r){
        if (unite(edges[i].first, edges[i].second)) cnt++;
    }
    return cnt == n - 1;
}

vector<int> find_roads(int _n, vector<int> u, vector<int> v) {
    n = _n;
    int m = v.size();

    for (int i = 0; i < m; i++){
        edges.push_back(make_pair(u[i], v[i]));
    }

	for (int mask = 0; mask < (1 << m); mask++){
        vector<int> r;
        for (int i = 0; i < m; i++){
            if (mask & (1 << i)) r.push_back(i);
        }
        if (check(r)){
            if (count_common_roads(r) == n - 1) return r;
        }
	}

	return {};
}

Compilation message (stderr)

simurgh.cpp: In function 'bool check(std::vector<int>&)':
simurgh.cpp:28:18: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   28 |     if (r.size() != n - 1) return false;
      |         ~~~~~~~~~^~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 0 / 17
• Subtask 3: 0 / 21
• Subtask 4: 0 / 19
• Subtask 5: 0 / 30