Submission #714890

#	Time	Username	Problem	Language	Result	Execution time	Memory
714890		aykhn	Stranded Far From Home (BOI22_island)	C++14	10 / 100	337 ms	616 KiB

island

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

#define OPT ios_base::sync_with_stdio(0); \
            cin.tie(0); \
            cout.tie(0)

#define pii pair<int,int>
#define pll pair<ll,ll>
#define endl "\n"
#define all(v) v.begin(), v.end()
#define mpr make_pair
#define pb push_back
#define ts to_string
#define fi first
#define se second
#define inf 0x3F3F3F3F
#define bpc __builtin_popcount
#define print(v) for(int i = 0; i < v.size(); i++) \
                    cout << v[i] << " "; \
                    cout<<endl;

/*
int ternarySearch(int l, int r, int key, int ar[])
{
    if (r >= l)
    {
        int mid1 = l + (r - l) / 3;
        int mid2 = r - (r - l) / 3;

        if (ar[mid1] == key) {
            return mid1;
        }
        if (ar[mid2] == key) {
            return mid2;
        }
        if (key < ar[mid1]) {
            return ternarySearch(l, mid1 - 1, key, ar);
        }
        else if (key > ar[mid2]) {
            return ternarySearch(mid2 + 1, r, key, ar);
        }
        else {
            return ternarySearch(mid1 + 1, mid2 - 1, key, ar);
        }
    }
    return -1;
}
*/
ll n;
vector<ll> v(2001);
vector<vector<ll>> adj(2001);

bool dijkstra(int a)
{
    priority_queue<pii, vector<pii>, greater<pii>> pq;
    pq.push({0, a});
    ll cnt = v[a];
    vector<bool> used(2001);
    bool flag = true;
    while (!pq.empty())
    {
        int w = pq.top().fi;
        int from = pq.top().se;
        used[from] = true;
        pq.pop();
        if (w <= cnt)
        {
            cnt += w;
            for (int i = 0; i < adj[from].size(); i++)
            {
                if (!used[adj[from][i]])
                {
                    pq.push({v[adj[from][i]], adj[from][i]});
                }
            }
        }
        else
        {
            flag = false;
            break;
        }
    }
    return flag;
}
vector<int> used;
vector<int> s;
vector<bool> ans;

int dfs1(int a)
{
    s[a] = v[a];
    used[a] = true;
    for (int i = 0; i < adj[a].size(); i++)
    {
        if (!used[adj[a][i]])
        {
            s[a] += dfs1(adj[a][i]);
        }
    }

    return s[a];
}
void dfs2(int a)
{
    used[a] = true;
    if (a == 1)
    {
        ans[a] = 1;
    }

    for (int i = 0; i < adj[a].size(); i++)
    {
        if (s[adj[a][i]] >= v[a] && ans[a] && !used[adj[a][i]])
        {
            ans[adj[a][i]] = 1;
            dfs2(adj[a][i]);
        }
        else
        {
            ans[adj[a][i]] = 0;
        }
    }
}
int main()
{
    ll m;
    cin >> n >> m;
    for (int i = 1; i <= n; i++)
    {
        cin >> v[i];
    }
    while (m--)
    {
        ll u, v;
        cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }

    if (n <= 2000 && m <= 2000)
    {
        for (int i = 1; i <= n; i++)
        {
            if (dijkstra(i)) cout << "1";
            else cout << "0";
        }
        return 0;
    }

    used.assign(n + 1, false);
    s.assign(n + 1, 0);
    ans.assign(n + 1, 0);

    dfs1(1);
    for (int i = 1; i <= n; i++) used[i] = false;
    dfs2(1);

    for (int i = 1; i <= n; i++)
    {
        cout << ans[i];
    }
    cout << endl;
}

Compilation message (stderr)

island.cpp: In function 'bool dijkstra(int)':
island.cpp:73:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   73 |             for (int i = 0; i < adj[from].size(); i++)
      |                             ~~^~~~~~~~~~~~~~~~~~
island.cpp: In function 'int dfs1(int)':
island.cpp:97:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   97 |     for (int i = 0; i < adj[a].size(); i++)
      |                     ~~^~~~~~~~~~~~~~~
island.cpp: In function 'void dfs2(int)':
island.cpp:115:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  115 |     for (int i = 0; i < adj[a].size(); i++)
      |                     ~~^~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 30
• Subtask 5: 0 / 35