Submission #31575

#	Time	Username	Problem	Language	Result	Execution time	Memory
31575		ngkan146	Hacker (BOI15_hac)	C++14	100 / 100	109 ms	6976 KiB

hac

#include <bits/stdc++.h>
using namespace std;
int n;
int sum = 0;
int a[500005],b[500005];
deque <int> dq;
int main(){
    scanf("%d",&n);
    for(int i=0;i<n;i++)
        scanf("%d",&a[i]), sum += a[i];
    for(int i=0;i<n/2;i++)
        b[0] += a[i];
    for(int i=1;i<n;i++)
        b[i] = b[i-1] - a[i-1] + a[(i+n/2-1+n)%n];
    for(int i=1;i<=n/2 + (n%2==1);i++){
        if (!dq.size()) dq.push_back(i);
        else{
            while(dq.size() && b[dq.back()] < b[i]) dq.pop_back();
            dq.push_back(i);
        }
    }

    int ans = 0;
    for(int i=0;i<n;i++){
        if (dq.front() == i) dq.pop_front();
        //cout << b[dq.front()] << endl;
        ans = max(ans, sum - b[dq.front()]);


        while(dq.size() && b[dq.back()] < b[(i+n/2 + (n%2==1)+1)%n]) dq.pop_back();
            dq.push_back((i+n/2 + (n%2==1)+1)%n);
    }
    cout << ans;
}

Compilation message (stderr)

hac.cpp: In function 'int main()':
hac.cpp:8:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
                   ^
hac.cpp:10:39: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d",&a[i]), sum += a[i];
                                       ^

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