Submission #780918

#	Time	Username	Problem	Language	Result	Execution time	Memory
780918		vjudge1	Election (BOI18_election)	C++17	82 / 100	73 ms	10356 KiB

election

#include<bits/stdc++.h>
#define taskname ""
#define el '\n'
#define fi first
#define sc second
#define pii pair<int, int>
#define all(v) v.begin(), v.end()
#define int long long
using namespace std;
#define Faster ios_base::sync_with_stdio(false);cin.tie(0);
const int maxn=1e5+7;
const int mod=1e9+9;
int n,a[maxn],q,b,c;
char x;
struct node
{
   int sum,pre,suf,seg;
}ST[4*maxn];
node operator +(node a,node b)
{
    node res;
    res.pre=max(a.sum+b.pre,a.pre);
    res.suf=max(a.suf+b.sum,b.suf);
    res.sum=a.sum+b.sum;
    res.seg=max({a.seg,b.seg,a.suf+b.pre});
    return res;
}
void construct(int id,int cl,int cr)
{
    if(cl==cr)
    {
        ST[id].pre=max(0LL,a[cl]);
        ST[id].suf=max(0LL,a[cl]);
        ST[id].seg=max(0LL,a[cl]);
        ST[id].sum=a[cl];
        return;
    }
    int mid=(cl+cr)/2;
    construct(2*id,cl,mid);
    construct(2*id+1,mid+1,cr);
    ST[id]=ST[2*id]+ST[2*id+1];
}
node query(int id,int cl,int cr,int l,int r)
{
    if(cl>r||cr<l) return {0,0,0,0};
    if(cl>=l&&cr<=r) return ST[id];
    int mid=(cl+cr)/2;
    return query(2*id,cl,mid,l,r)+query(2*id+1,mid+1,cr,l,r);
}
signed main()
{
    if (fopen(taskname".INP","r"))
    {
        freopen(taskname".INP","r",stdin);
        freopen(taskname".OUT","w",stdout);
    }
    Faster
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>x;
        if(x=='C') a[i]=1;
        else a[i]=-1;
    }
    construct(1,1,n);
    cin>>q;
    while(q--)
    {
        cin>>b>>c;
        node w=query(1,1,n,b,c);
        cout<<w.seg-w.sum<<"\n";
    }
}

Compilation message (stderr)

election.cpp: In function 'int main()':
election.cpp:54:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   54 |         freopen(taskname".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
election.cpp:55:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   55 |         freopen(taskname".OUT","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 28 / 28
• Subtask 2: 54 / 54
• Subtask 3: 0 / 18