Submission #753935

#	Time	Username	Problem	Language	Result	Execution time	Memory
753935		Abito	Stranded Far From Home (BOI22_island)	C++14	20 / 100	543 ms	48396 KiB

island

#include <bits/stdc++.h>
#define F first
#define S second
#define pb push_back
#define ppb pop_back
#define ep insert
#define endl '\n'
#define elif else if
#define pow pwr
#define sqrt sqrtt
#define int long long
typedef unsigned long long ull;
using namespace std;
const int N=2e5+5;
int n,m,a[N],dis[N],par[N],dp[N],st[25][N],p[N],lg[N],L[N],R[N];
vector<int> adj[N],v;
bool cmp(int x,int y){
    return dis[x]<dis[y];
}
bool cmpp(int x,int y){
    return a[x]>a[y];
}
void build(){
    for (int i=0;i<=n+1;i++) st[0][i]=a[i];
    for (int i=1;i<25;i++){
        for (int j=0;j+(1<<i)<=n+2;j++){
            st[i][j]=max(st[i-1][j],st[i-1][j+(1<<(i-1))]);
        }
    }return;
}
int query(int l,int r){
    if (l>r) swap(l,r);
    int i=lg[r-l+1];
    return max(st[i][l],st[i][r-(1<<i)+1]);
}
bool check(int source){
    priority_queue<pair<int,int>> pq;
    bool vis[n+5];
    memset(vis,0,sizeof(vis));
    int c=a[source];
    for (auto u:adj[source]) pq.push({-a[u],u});
    vis[source]=true;
    while (!pq.empty()){
        pair<int,int> x=pq.top();
        pq.pop();
        x.F*=-1;
        if (vis[x.S]) continue;
        if (x.F>c) break;
        vis[x.S]=true;
        c+=x.F;
        for (auto u:adj[x.S]) pq.push({-a[u],u});
    }
    bool ok=true;
    for (int i=1;i<=n;i++){
        if (vis[i]) continue;
        ok=false;
        break;
    }return ok;
}
void dfs(int node,int d,int p){
    dis[node]=d;
    dp[node]=a[node];
    par[node]=p;
    for (auto u:adj[node]){
        if (u==p) continue;
        dfs(u,d+1,node);
        dp[node]+=dp[u];
    }return;
}
int32_t main(){
    ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
    for (int i=2;i<N;i++) lg[i]=lg[i/2]+1;
    cin>>n>>m;
    bool sub3=true,sub2=true;
    for (int i=1;i<=n;i++) cin>>a[i];
    for (int i=1;i<n;i++){
        if (a[i]>=a[i+1]) continue;
        sub2=false;
    }
    for (int i=1;i<=m;i++){
        int x,y;
        cin>>x>>y;
        adj[x].pb(y);
        adj[y].pb(x);
        if (abs(x-y)!=1) sub3=false;
    }
    for (int i=2;i<=n;i++){
        int x=0;
        for (auto u:adj[i]) x+=bool(u<i);
        if (x!=1) sub2=false;
    }
    if (n<=2000 && m<=2000){
        for (int i=1;i<=n;i++) cout<<check(i);
        return 0;
    }
    if (sub2){
        dfs(1,0,0);
        for (int i=2;i<=n;i++) v.pb(i);
        sort(v.begin(),v.end(),cmp);
        for (auto node:v){
            if (dp[node]<a[par[node]]) continue;
            dp[node]=dp[par[node]];
        }
        for (int i=1;i<=n;i++) cout<<bool(dp[i]==dp[1]);
        return 0;
    }
    if (sub3){
        a[0]=LLONG_MAX,a[n+1]=a[0];
        for (int i=1;i<=n;i++) p[i]=p[i-1]+a[i];
        build();
        vector<int> v;
        for (int i=1;i<=n;i++) v.pb(i);
        sort(v.begin(),v.end(),cmpp);
        for (auto u:v){
            int l=0,r=u,mid;
            while (l<=r){
                //cout<<l<<' '<<r<<' ';
                mid=(l+r)/2;
                int x=query(mid,u);
                //cout<<x<<endl;
                if (x<=a[u]){
                    L[u]=mid;
                    r=mid-1;
                }else l=mid+1;
            }
            l=u,r=n+1;
            while (l<=r){
                mid=(l+r)/2;
                int x=query(mid,u);
                if (x<=a[u]){
                    R[u]=mid;
                    l=mid+1;
                }else r=mid-1;
            }dp[u]=p[R[u]]-p[L[u]-1];
            int x=R[u]+1,y=L[u]+1;
            if (a[x]>a[y]) swap(x,y);
            for (int k=1;k<=20;k++){
                if (dp[u]>=a[x]){
                    L[u]=min(L[u],L[x]);
                    dp[u]=p[R[u]]-p[L[u]-1];
                }
                if (dp[u]>=a[y]){
                    R[u]=max(R[u],R[y]);
                    dp[u]=p[R[u]]-p[L[u]-1];
                }
            }
        }
        for (int i=1;i<=n;i++) cout<<bool(dp[i]==p[n]);
        return 0;
    }
    return 0;
}

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