Submission #888590

#	Time	Username	Problem	Language	Result	Execution time	Memory
888590		yfrank792	Election (BOI18_election)	C++14	82 / 100	141 ms	36180 KiB

election

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

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef queue<int> qi;
typedef set<int> si;

typedef priority_queue<int> pqi;
typedef priority_queue<ll> pql;
typedef priority_queue<int,vi,greater<int> > pqi_g;
typedef priority_queue<ll,vll,greater<ll> > pql_g;

#define F first
#define S second
#define PB push_back
#define PF push_front
#define MP make_pair
#define FOR(i,a,b) for (int i=a; i<=b; i++)
#define _FOR(i,a,b) for (int i=a; i>=b; i--)
#define F0R(i,a,b,x) for (int i=a; i<=b; i+=x)
#define FOR_(x,v) for (auto x : v)
#define F0R_(x,v) for (auto &x : v)

const int INF = 0x3f3f3f3f;
const int maxn = 5e5+5;
const ll MOD = 1e9+7;

//? link: https://oj.uz/problem/view/BOI18_election

//? sol: 

int n, q;

class segtree {
    struct node {ll mx_pre,mx_suf,sum,ans;} d[maxn];
    private:
        ll inline ls(ll x) {return x<<1;}
        ll inline rs(ll x) {return x<<1|1;}
        node inline op(node &l,node &r) {
            return {
                max(l.mx_pre, l.sum+r.mx_pre),
                max(r.mx_suf, r.sum+l.mx_suf),
                l.sum + r.sum,
                max(max(l.ans+r.sum, l.sum+r.ans), l.mx_pre+r.mx_suf)
            };
        }
    public:
        ll a[maxn];     // 1 if T, -1 if C
        void init(ll s=1,ll t=n,ll p=1) {
            if (s==t) {
                ll tmp = (ll)a[s];
                d[p] = {max(tmp,0ll),max(tmp,0ll),tmp,max(tmp,0ll)};    // mx_pre, mx_suf, sum, ans
                // note: mx_pre and mx_suf can be 0 when it's C (taking prefix/suffix sum of no elements)
                return;
            }
            ll mid = s + ((t-s)>>1);
            init(s, mid, ls(p));
            init(mid+1, t, rs(p));
            d[p] = op(d[ls(p)], d[rs(p)]);
        }
        node query(ll l,ll r,ll s=1,ll t=n,ll p=1) {      // query(l,r)
            if (l<=s && t<=r) return d[p];
            ll mid = s + ((t-s)>>1);
            node lch, rch;
            if (l<=mid) lch=query(l,r,s,mid,ls(p));
            else lch={0,0,0,0};
            if (r>mid) rch=query(l,r,mid+1,t,rs(p));
            else rch={0,0,0,0};
            return op(lch,rch);
        }
} st;

int a[maxn];

int main()
{
    // faster cin/cout
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    // freopen("c.in","r",stdin);

    cin >> n;
    FOR(i,1,n) {
        char c; cin>>c;
        st.a[i] = (c=='C'? -1:1);
    }
    st.init();

    cin >> q;
    FOR(_,1,q) {
        int l,r; cin>>l>>r;
        cout << st.query(l,r).ans << endl;
    }

    return 0;   
}

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