Submission #536345

#	Time	Username	Problem	Language	Result	Execution time	Memory
536345		Evang	Election (BOI18_election)	C++17	100 / 100	379 ms	26640 KiB

election

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

#ifdef _DEBUG
#define dout(x) clog << "Line " << __LINE__ << ": " << #x << "=" << (x) << el
#else
#define dout(x)
#endif

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define uid(a,b) uniform_int_distribution<int>(a,b)(rng)

#define ins insert
#define ssize(x) (int((x).size()))
#define bs(args...) binary_search(args)
#define lb(args...) lower_bound(args)
#define ub(args...) upper_bound(args)
#define all(x) (x).begin(),(x).end()
#define mp(a, b) make_pair(a, b)
#define mt(args...) make_tuple(args)
#define pb push_back
#define eb emplace_back
#define ff first
#define ss second
#define die exit(0)

template<typename T>
using vc = vector<T>;
template<typename T>
using uset = unordered_set<T>;
template<typename A, typename B>
using umap = unordered_map<A, B>;
template<typename T, typename Comp>
using pq = std::priority_queue<T, vc<T>, Comp>;
template<typename T>
using maxpq = pq<T, less<T>>;
template<typename T>
using minpq = pq<T, greater<T>>;
template<typename T>
using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

using db = double;
using ld = long double;
using ll = long long;
using ull = unsigned long long;
using pi = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vc<int>;
using vll = vc<ll>;
using vpi = vc<pi>;
using vpll = vc<pll>;
using str = string;

constexpr char el = '\n';
constexpr char sp = ' ';
constexpr int inf = 0x3f3f3f3f;
constexpr ll llinf = 0x3f3f3f3f3f3f3f3fLL;
// ---------------------------------------------------------------------


int n, q;
struct node{
    int sum, pre, suf, ans;
} tr[1'000'005];

node cmb(node x, node y){
    return node{
            x.sum+y.sum,
            max(x.sum+y.pre, x.pre),
            max(x.suf+y.sum, y.suf),
            max({x.pre+y.suf, x.sum+y.ans, x.ans+y.sum})
    };
}

void pull(int i){
    tr[i] = cmb(tr[2*i], tr[2*i+1]);
//    tr[i].sum = tr[2*i].sum + tr[2*i+1].sum;
//    tr[i].pre = max(tr[2*i].sum+tr[2*i+1].pre, tr[2*i].pre);
//    tr[i].suf = max(tr[2*i].suf+tr[2*i+1].sum, tr[2*i+1].suf);
//    tr[i].ans = max({tr[2*i].pre + tr[2*i+1].suf,
//            tr[2*i].sum+tr[2*i+1].ans, tr[2*i].ans+tr[2*i+1].ans});
}

int qry(int l, int r){
    l += n-1;
    r += n-1;
    node le{0, 0, 0, 0}, ri{0, 0, 0, 0};
    while(l<=r){
        if(l&1){
            le = cmb(le, tr[l]);
            ++l;
        }
        if(r&1^1){
            ri = cmb(tr[r], ri);
            --r;
        }
        l /= 2;
        r /= 2;
    }
    return cmb(le, ri).ans;
}

signed main() {
    ios::sync_with_stdio(0); cin.tie(0);
    cout << fixed; clog << fixed; clog << unitbuf;
#ifdef _DEBUG
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    freopen("debug.txt", "w", stderr);
#else
    //freopen(".in", "r", stdin);
    //freopen(".out", "w", stdout);
#endif

    cin >> n;
    for(int i = n; i < 2*n; ++i){
        char c;
        cin >> c;
        tr[i].sum = c=='T'? 1:-1;
        tr[i].ans = tr[i].suf = tr[i].pre = max(0, tr[i].sum);
    }
    for(int i = n-1; i > 0; --i)
        pull(i);

    cin >> q;
    while(q--){
        int l, r;
        cin >> l >> r;
        cout << qry(l, r) << el;
    }
}

Compilation message (stderr)

election.cpp: In function 'int qry(int, int)':
election.cpp:94:13: warning: suggest parentheses around arithmetic in operand of '^' [-Wparentheses]
   94 |         if(r&1^1){
      |            ~^~

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