Submission #1050859

#	Time	Username	Problem	Language	Result	Execution time	Memory
1050859		sofijavelkovska	Stranded Far From Home (BOI22_island)	C++17	10 / 100	225 ms	58960 KiB

island

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

const int MAXN=300000;
// 2e5 ??

int n, m;
int a[MAXN];
vector<int> adj[MAXN];
int link[MAXN], csize[MAXN], cindex[MAXN];
long long sum[MAXN];
set<pair<int, int> > neighbours[MAXN];

bool compare(int x, int y)
{
    return a[x]<a[y];
}

int find(int x)
{
    if (link[x]==x)
        return x;

    return link[x]=find(link[x]);
}

void unite(int x, int y)
{
    int xt=x, yt=y;
    x=find(x);
    y=find(y);
    if (csize[x]<csize[y])
        swap(x, y);
    csize[x]=csize[x]+csize[y];
    sum[x]=sum[x]+sum[y];
    link[y]=x;
    if (neighbours[cindex[x]].size()<neighbours[cindex[y]].size())
    {
        for (auto t : neighbours[cindex[x]])
            neighbours[cindex[y]].insert(t);
        neighbours[cindex[y]].erase({a[xt], xt});
        neighbours[cindex[y]].erase({a[yt], yt});
        neighbours[cindex[x]].clear();
        cindex[x]=cindex[y];
    }
    else
    {
        for (auto t : neighbours[cindex[y]])
            neighbours[cindex[x]].insert(t);
        neighbours[cindex[x]].erase({a[xt], xt});
        neighbours[cindex[x]].erase({a[yt], yt});
        neighbours[cindex[y]].clear();
        cindex[y]=cindex[x];
    }

    return;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> n >> m;
    for (int i=0; i<n; i++)
        cin >> a[i];
    for (int i=0; i<m; i++)
    {
        int x, y;
        cin >> x >> y;
        adj[x-1].push_back(y-1);
        adj[y-1].push_back(x-1);
    }
    int sorted[n];
    for (int i=0; i<n; i++)
        sorted[i]=i;
    sort(sorted, sorted+n, compare);
    for (int i=0; i<n; i++)
    {
        link[i]=i;
        csize[i]=1;
        sum[i]=a[i];
        for (auto x : adj[i])
            neighbours[i].insert({a[x], x});
        cindex[i]=i;

    }
    bool possible[n];
    for (int i=0; i<n; i++)
        possible[i]=true;
    queue<int> q;
    for (int i=0; i<n; i++)
    {
        int x=sorted[i];
        for (auto y : adj[x])
            if (a[y]<=a[x] && find(x)!=find(y))
                unite(x, y);
        int leader=find(x);
        if (neighbours[cindex[leader]].empty())
            continue;
        auto it=neighbours[cindex[leader]].begin();
        //cout << "x " << x << '\n';
        //cout << "sum max " << sum[leader] << ' ' << (*it).first << '\n';
        if (sum[leader]>=(*it).first)
            continue;
        possible[x]=false;
        q.push(x);
        while (!q.empty())
        {
            int y=q.front();
            q.pop();
            for (auto t : adj[y])
                if (a[t]<=a[x] && possible[t])
                {
                    possible[t]=false;
                    q.push(t);
                }
        }
    }
    for (int i=0; i<n; i++)
        cout << possible[i];

    return 0;
}

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