Submission #826126

#	Time	Username	Problem	Language	Result	Execution time	Memory
826126		LittleCube	Thousands Islands (IOI22_islands)	C++17	0 / 100	2 ms	2900 KiB

islands

#include "islands.h"
#include <bits/stdc++.h>
#define ll long long
#define pii pair<int, int>
#define F first
#define S second
using namespace std;

namespace
{
    int K;
    vector<int> path;
    int vis[100000], use[200000], p[100000], pe[100000], deg[100000];
    vector<pii> E[100000];
    void dfs(int u)
    {
        vis[u] = 1;
        for (auto [v, i] : E[u])
            if (vis[v] == 0)
            {
                p[v] = u;
                pe[v] = i;
                dfs(v);
                deg[u]++;
            }
            else if (vis[v] == 1 && i != pe[u] ^ 1)
                use[i] = 1;
    }
}

variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V)
{
    for (int i = 0; i < M; i++)
        E[U[i]].emplace_back(pii(V[i], i));

    p[0] = -1;
    dfs(0);
    if (*max_element(deg, deg + N) >= 2)
    {
        int k = max_element(deg, deg + N) - deg;
        vector<int> down, branch, sol;
        for (int i = 0; i < N; i++)
            if(p[i] == k)
                branch.emplace_back(pe[i]);
        while(k)
        {
            down.emplace_back(pe[k]);
            k = p[k];
        }
        reverse(down.begin(), down.end());
        sol.insert(sol.end(), down.begin(), down.end());
        for (int i : branch)
            sol.emplace_back(i), sol.emplace_back(i ^ 1);
        for (int i : branch)
            sol.emplace_back(i ^ 1), sol.emplace_back(i);
        reverse(down.begin(), down.end());
        for (int i : down)
            sol.emplace_back(i ^ 1);
    }
    if (*max_element(use, use + M) >= 1)
        return true;
    return false;
}

Compilation message (stderr)

islands.cpp: In function 'void {anonymous}::dfs(int)':
islands.cpp:26:39: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
   26 |             else if (vis[v] == 1 && i != pe[u] ^ 1)
      |                                     ~~^~~~~~~~
islands.cpp: At global scope:
islands.cpp:11:9: warning: '{anonymous}::K' defined but not used [-Wunused-variable]
   11 |     int K;
      |         ^

• Subtask 1: 0 / 5
• Subtask 2: 0 / 5
• Subtask 3: 0 / 21
• Subtask 4: 0 / 24
• Subtask 5: 0 / 45