Submission #1365752

#	Time	Username	Problem	Language	Result	Execution time	Memory
1365752		retarde	Stranded Far From Home (BOI22_island)	C++20	100 / 100	270 ms	82840 KiB

island

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

#define pb push_back
#define pf push_front
#define mp make_pair
#define fi first
#define se second
#define int long long
#define all(x) (x).begin(), (x).end()

typedef long double ld;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<bool> vb;
typedef vector<vector<int>> vvi;
typedef vector<vector<bool>> vvb;
typedef vector<vector<ll>> vvll;
typedef vector<string> vs;
typedef vector<vector<string>> vvs;
typedef vector<char> vc;
typedef vector<vector<char>> vvc;
typedef map<int, int> mii;
typedef unordered_map<int, int> umii;

const int mod = 1e9 + 7;
const int inf = INTMAX_MAX;
const bool tc = false;

int n, m;
vi adj[200005]; int a[200005];

class DisjointSets {
  private:
	vector<int> parents;
	vector<int> sizes;

  public:
    vector<int> sumsize;
    vector<set<int>> cands;
	DisjointSets(int size) : parents(size), sizes(size, 1), sumsize(size), cands(size) {
		for (int i = 0; i < size; i++) {
            parents[i] = i;
            sumsize[i] = a[i];
            cands[i].insert(i);
        }
	}

	/** @return the "representative" node in x's component */
	int find(int x) { return parents[x] == x ? x : (parents[x] = find(parents[x])); }

    set<int> get(int x) { return cands[find(x)]; }

	/** @return whether the merge changed connectivity */
	bool unite(int x, int y) {
		int x_root = find(x);
		int y_root = find(y);
		if (x_root == y_root) { return false; }

        bool mrg = false;
        if (a[x] <= sumsize[y_root]) {
            mrg = true;
        } else {
            cands[y_root].clear();
        }

		if (sizes[x_root] < sizes[y_root]) { swap(x_root, y_root); }
        for (auto &cd : cands[y_root]) cands[x_root].insert(cd);
		sizes[x_root] += sizes[y_root];
		parents[y_root] = x_root;
        sumsize[x_root] += sumsize[y_root];

		return true;
	}

	/** @return whether x and y are in the same connected component */
	bool connected(int x, int y) { return find(x) == find(y); }
};

inline void solve() {
    cin >> n >> m;
    vector<pii> nodes;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        nodes.pb({a[i], i});
    }
    for (int i = 0; i < m; i++) {
        int x, y; cin >> x >> y;
        x--; y--; adj[x].pb(y); adj[y].pb(x);
    }

    sort(all(nodes)); DisjointSets dsu(n);
    for (auto &x : nodes) {
        int u = x.second;
        for (auto &v : adj[u]) {
            if (a[v] > a[u]) continue;
            if (dsu.connected(u, v)) continue;
            dsu.unite(u, v);
        }
    }

    string ans(n, '0');
    for (auto &x : dsu.cands[dsu.find(0)]) ans[x] = '1';
    cout << ans << '\n'; 
}

void setIO(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}

signed main() {
    ios::sync_with_stdio(false);
    cout.tie(0);
    cin.tie(0);
    //setIO();

    int t = 1;
    if (tc) {
        cin >> t;
    }

    while (t--) {
        solve();
    }
}

Compilation message (stderr)

island.cpp: In function 'void setIO(std::string)':
island.cpp:111:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  111 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
island.cpp:112:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  112 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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