Submission #17665

#	Time	Username	Problem	Language	Result	Execution time	Memory
17665		ZiyaZa	Divide and conquer (IZhO14_divide)	C++14	100 / 100	69 ms	7580 KiB

divide

#include <iostream>
#include <cstdio>
#define pairr pair<long long,int>
#define f first
#define s second
using namespace std;
long long sumg[100010],sume[100010],a;
int n,x[100010],g[100010],e[100010],il,ir;
pairr sl[100010],sr[100010];
long long solve(int l, int r)
{
    if (l==r)
    {
        return g[l];
    }
    if (l==r-1)
    {
        if (e[l]+e[r]>=x[r]-x[l]) return g[l]+g[r];
        return max(g[l],g[r]);
    }
    int mid=(l+r)/2;
    long long ans=max(solve(l,mid),solve(mid+1,r));
    il=0;
    ir=0;
    for (int i=mid;i>=l;i--)
    {
        a=(i==0 ? sume[mid] : sume[mid]-sume[i-1])-(x[mid]-x[i]);
        while (il>0 && a>=sl[il-1].f)
        {
            il--;
        }
        sl[il].f=a;
        sl[il].s=i;
        il++;
    }
    for (int i=mid+1;i<=r;i++)
    {
        a=sume[i]-sume[mid]-(x[i]-x[mid+1]);
        while (ir>0 && a>=sr[ir-1].f)
        {
            ir--;
        }
        sr[ir].f=a;
        sr[ir].s=i;
        ir++;
    }

    for (int i=0;i<il;i++)
    {
        int flag=0;
        for (int j=ir-1;j>=0;j--)
        {
            if (sl[i].f+sr[j].f>=x[mid+1]-x[mid])
            {
                ans=max(ans,sl[i].s==0 ? sumg[sr[j].s] : sumg[sr[j].s]-sumg[sl[i].s-1]);
                flag=1;
                break;
            }
        }
        if (flag==0) break;
    }
    return ans;
}

int main()
{
    cin>>n;
    for (int i=0;i<n;i++)
    {
        scanf("%d%d%d",&x[i],&g[i],&e[i]);
        if (i==0)
        {
            sumg[i]=g[i];
            sume[i]=e[i];
        }
        else
        {
            sumg[i]=sumg[i-1]+g[i];
            sume[i]=sume[i-1]+e[i];
        }
    }
    cout<<solve(0,n-1)<<endl;
    return 0;
}

• Subtask 1: 17 / 17
• Subtask 2: 31 / 31
• Subtask 3: 52 / 52