제출 #764289

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
764289		raysh07	수천개의 섬 (IOI22_islands)	C++17	컴파일 에러	0 ms	0 KiB

islands

#include "islands.h"
#include <variant>
#include <bits/stdc++.h>
using namespace std;

const int N = 1e5 + 69;
int deg[N];
bool vis[N];
vector <pair<int, int>> adj[N];
vector <int> path, ok;
map <pair<int, int> , int> mp;
int n;

void dfs(int u){
    vis[u] = true;
    path.push_back(u);
    if (deg[u] >= 3){
        ok = path;
    }
    for (auto [v, i] : : adj[u]){
        if (!vis[v]) dfs(v);
    }
    path.pop_back();
}

void get(vector <int> &ans, int x, int y, int z){
    ans.push_back(mp[{x, y}]);
    ans.push_back(mp[{y, x}]);
    ans.push_back(mp[{x, z}]);
    ans.push_back(mp[{z, x}]);
    ans.push_back(mp[{y, x}]);
    ans.push_back(mp[{x, y}]);
    ans.push_back(mp[{z, x}]);
    ans.push_back(mp[{z, x}]);
}

variant<bool, vector<int>> find_journey(int nn, int m, vector<int> u, vector<int> v) {
    n = nn;
    for (int i = 0; i < m; i+=2){
        adj[u[i]].push_back({v[i], i});
        adj[v[i]].push_back({u[i], i});
        mp[{u[i], v[i]}] = i;
        mp[{v[i], u[i]}] = i + 1;
        deg[u[i]]++;
        deg[v[i]]++;
    }
    
    vector <int> ans;
    
    if (deg[0] >= 2){
        int v1 = adj[0][0].first;
        int v2 = adj[0][1].first;
        
        get(ans, 0, v1, v2);
        return ans;
    }
    
    dfs(0);
    if (ok.size() == 0) return false;
    
    vector <int> a1;
    for (int i = 1; i < ok.size(); i++) a1.push_back(mp[{ok[i - 1], ok[i]}]);
    ans = a1;
    int v1, v2, v3, x, y;
    x = ok.back();
    y = ok[ok.size() - 2];
    
    v1 = adj[x][0].first;
    v2 = adj[x][1].first;
    v3 = adj[x][2].first;
    
    if (v1 != y && v2 != y)
    get(ans, x, v1, v2);
    else if (v1 == y) get(ans, x, v2, v3);
    else get(ans, x, v1, v3);
    
    reverse(a1.begin(), a1.end());
    for (auto x : a1) ans.push_back(x);
    return ans;
}

컴파일 시 표준 에러 (stderr) 메시지

islands.cpp: In function 'void dfs(int)':
islands.cpp:20:24: error: expected primary-expression before ':' token
   20 |     for (auto [v, i] : : adj[u]){
      |                        ^
islands.cpp:20:23: error: expected ')' before ':' token
   20 |     for (auto [v, i] : : adj[u]){
      |         ~             ^~
      |                       )
islands.cpp:20:24: error: expected primary-expression before ':' token
   20 |     for (auto [v, i] : : adj[u]){
      |                        ^
islands.cpp: In function 'std::variant<bool, std::vector<int, std::allocator<int> > > find_journey(int, int, std::vector<int>, std::vector<int>)':
islands.cpp:62:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   62 |     for (int i = 1; i < ok.size(); i++) a1.push_back(mp[{ok[i - 1], ok[i]}]);
      |                     ~~^~~~~~~~~~~