Submission #1205775

#	Time	Username	Problem	Language	Result	Execution time	Memory
1205775		Aiperiii	Stranded Far From Home (BOI22_island)	C++20	15 / 100	107 ms	30652 KiB

island

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define all(x) x.begin(),x.end()
#define ff first
#define ss second
#define pb push_back
const int N=2e5+5;
vector <int> g[N];
int sum[N],a[N],ok[N];
pair <int,int> t[N*4];
int n,m;
void build(int v,int tl,int tr){
    if(tl==tr){
        t[v]={a[tl],tl};
        return;
    }
    int tm=(tl+tr)/2;
    build(v*2,tl,tm);
    build(v*2+1,tm+1,tr);
    if(t[v*2].ff>=t[v*2+1].ff){
        t[v].ff=t[v*2].ff;
        t[v].ss=t[v*2].ss;
    }
    else{
        t[v].ff=t[v*2+1].ff;
        t[v].ss=t[v*2+1].ss;
    }
    
}
pair <int,int> get(int v,int tl,int tr,int l,int r){
    if(r<tl or tr<l)return {-1e18,0};
    if(l<=tl && tr<=r) return t[v];
    int tm=(tl+tr)/2;
    pair <int,int> p1=get(v*2,tl,tm,l,r);
    pair <int,int> p2=get(v*2+1,tm+1,tr,l,r);
    if(p1.ff>=p2.ff){
        return p1;
    }
    else{
        return p2;
    }
    
}
void rec(int l,int r){
    
    if(l==r){
        ok[l]=1;
        return;
    }
    pair <int,int> x=get(1,1,n,l,r);
    int ind=x.ss;
    int mx=x.ff;
    
    ok[ind]=1;
    int sum1=(sum[r]-sum[l-1])-(sum[r]-sum[ind-1]);
    int sum2=(sum[r]-sum[l-1])-(sum[ind]-sum[l-1]);
    if(sum1>=mx && l<=ind-1){
        rec(l,ind-1);
    }
    if(sum2>=mx && ind+1<=r){
        rec(ind+1,r);
    }
}
signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    
    cin>>n>>m;
    
    for(int i=1;i<=n;i++){
        cin>>a[i];
    }
    build(1,1,n);
    
    for(int i=1;i<=n;i++){
        sum[i]=sum[i-1]+a[i];
    }
    while(m--){
        int u,v;
        cin>>u>>v;
        g[u].pb(v);
        g[v].pb(u);
    }
    rec(1,n);
    for(int i=1;i<=n;i++)cout<<ok[i];
}
/*
 4 4
 2 2 4 3
 1 2
 1 3
 2 3
 3 4
 
 4 3
 4 2 2 1
 1 2
 3 2
 4 1
 
 10 9
 10 9 8 7 4 4 3 2 1 1
 1 2
 1 3
 2 4
 3 5
 5 7
 5 8
 7 9
 8 10
 3 6
 
 1110101000
 
 
   1 1 1 1      1
 2 3 4 5 10 3 2 6 3
*/

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