Submission #129986

#	Time	Username	Problem	Language	Result	Execution time	Memory
129986		Vardanyan	Hacker (BOI15_hac)	C++14	100 / 100	272 ms	28536 KiB

hac

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

const int N = 500*1000+5;
int a[N];
long long pref[N];
long long ANS[N];
long long prefmx[N];
long long sufmx[N];
long long t[4*N];
void update(int v,int s,int e,int l,int r,long long val){
    if(l>r) return;
    if(s == l && e == r){
        t[v] = val;
        return;
    }
    int m = (s+e)/2;
    update(v*2,s,m,l,min(m,r),val);
    update(v*2+1,m+1,e,max(l,m+1),r,val);
    t[v] = max(t[v*2],t[v*2+1]);
}
long long get(int v,int s,int e,int l,int r){
    if(l>r) return 0;
    if(s == l && e == r) return t[v];
    int m = (s+e)/2;
    return max(get(v*2,s,m,l,min(m,r)),
           get(v*2+1,m+1,e,max(l,m+1),r));
}
int main(){
    ios_base::sync_with_stdio(false);
    int n;
    cin>>n;
    long long all = 0;
    for(int i = 1;i<=n;i++) {
        cin>>a[i];
        all+=a[i];
        pref[i] = pref[i-1]+a[i];
    }
    for(int j = 1;j<=n;j++){
            int jj = j;
            int qn = 0;
            long long cur = 0;
            int l = j;
            int r = j+n/2-1;
            if(r>n) r = (r-n);
            if(r>=l){
               // if(i<l || i>r){
                    cur = pref[r]-pref[l-1];
               // }
            }
            else{
              //  if(i>r && i<l){
                    cur+=(pref[r]);
                    cur+=(pref[n]-pref[l-1]);
             //   }
            }
//            mx = max(mx,cur);
            ANS[j] = cur;
            update(1,1,n,j,j,cur);
    }
    for(int i = 1;i<=n;i++){
        prefmx[i] = max(prefmx[i-1],ANS[i]);
    }
    for(int i = n;i>=1;i--){
        sufmx[i] = max(sufmx[i+1],ANS[i]);
    }
    long long ans = 0;
    for(int i = 1;i<=n;i++){
        int pos = i-n/2;
        long long cur = 0;
        if(pos>=1){
            cur = max(cur,prefmx[pos]);
            cur = max(cur,sufmx[i+1]);
        }
        else{
            pos = n+pos;
            long long x = get(1,1,n,i+1,pos);
            cur = max(cur,x);
        }
        ans = max(ans,all-cur);
    }
    cout<<ans<<endl;
    return 0;
}

Compilation message (stderr)

hac.cpp: In function 'int main()':
hac.cpp:40:17: warning: unused variable 'jj' [-Wunused-variable]
             int jj = j;
                 ^~
hac.cpp:41:17: warning: unused variable 'qn' [-Wunused-variable]
             int qn = 0;
                 ^~

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 40 / 40