Submission #1121720

#	Time	Username	Problem	Language	Result	Execution time	Memory
1121720		vjudge1	Stranded Far From Home (BOI22_island)	C++17	0 / 100	1092 ms	494424 KiB

island

#include <bits/stdc++.h>

#define ll long long
#define all(x) x.begin(), x.end()
#define in insert
#define F first
#define S second
#define ppf pop_front
#define pb push_back
#define ppb pop_back
#define pf push_front
#define pii pair <int, int>
#define pll pair <ll, ll>
#define boost() ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define sz(x) (int)x.size()
#define int ll
using namespace std;

const int N = 2e5+123;
const ll mod = 1e9+7;

vector<int> g[N];
pll a[N];
bool ans[N];
int ls[N];
int us[N];

void dfs(int v,int p){
    ls[v]=a[v].F;
    for(int to : g[v]){
        if(to == p)
            continue;
        dfs(to , v);
        ls[v]+=ls[to];
        
    }
}
void dfs2(int v , int p){
    if(!ans[p])
        ans[v]=0;
    else{
        ans[v]=(ls[v] >= a[p].F);
    }
    for(int to : g[v]){
        if(to == p)
            continue;
        dfs2(to , v);
        
    }
}

void solve() {
    int n,m;
    cin >> n >> m;
    
    for(int i=1 ; i <= n ; i++){
        cin >> a[i].F;
        a[i].S=i;
    }
    
    for(int i=1 ; i <= m ; i++){
        int v,u;
        cin >> v >> u;
        g[u].pb(v);
        g[v].pb(u);
    }
    // for(int i=1 ; i <= n ; i++){
    //     cout << a[i].F << " " << a[i].S << endl;
    // }
    
    
    if(n <= 2000 && m <= 2000){
        sort(a+1 , a+1+n);
        for(int i=n ; i >= 1 ; i--){
            int j=a[i].S;
            us[j]=j;
            set<pll> st;
            int cnt=0;
            st.in({0 , j});
            while(!st.empty()){
                pll o=*st.begin();
                st.erase(o);
                int x=o.F;
                int v=o.S;
                if(cnt < x){
                    ans[j]=0;
                    break;
                }
                if(ans[v] == 1){
                    ans[j]=1;
                    break;
                }
                cnt+=a[v].F;
                for(int to : g[v]){
                    if(us[to] != j){
                        us[to]=j;
                        st.in({a[to].F , to});
                    }
                    
                }
                if(st.empty()){
                    ans[j]=1;
                }
            }
        }
        for(int i=1 ; i <= n ; i++){
            cout << ans[i];
        }
        return;
    }
    
    ans[0]=1;
    dfs(1 , 0);
    dfs2(1 , 0);
    for(int i=1 ; i <= n ; i++){
        cout << ans[i];
    }
    
}
/*
4 4
2 2 4 3
1 2
1 3
2 3
3 4
*/
signed main() {
    boost();
    int tt=1;
    //cin >> tt;
    while (tt--) {
        solve();
    }
    return 0;
}

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