Submission #619785

#	Time	Username	Problem	Language	Result	Execution time	Memory
619785		welleyth	Election (BOI18_election)	C++17	0 / 100	4 ms	468 KiB

election

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;

#define int long long
#define mp make_pair
#define pb push_back

#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx2")

constexpr int INF = (int)2e9;
constexpr int N = (int)5e5 + 111;
constexpr int md = (int)998244353;
constexpr int mdPower = (int)1e9+7 - 1;
constexpr double eps = 1e-7;

typedef __int128 _uint;
typedef long long ll;

mt19937_64 rnd(time(nullptr));

void add(int& a,int b){
    a += b; if(a >= md) a -= md;
}
void sub(int& a,int b){
    a -= b; while(a < 0) a += md;
}
void add(__int128& a,int b){
    a += b;
}
void sub(__int128& a,int b){
    a -= b;
}

int bpow(int a,int b){
    if(b == 0)
        return 1;
    if(b % 2 == 0){
        int t = bpow(a,b>>1);
        return 1ll*t*t%md;
    }
    return 1ll * a*bpow(a,b-1) % md;
}

int inv(int a){
    return bpow(a,md-2);
}

//int fac[N],invfac[N];
//
//void init(){
//    fac[0] = 1;
//    for(int i = 1; i < N; i++){
//        fac[i] = (fac[i-1] * i) % md;
//    }
//    invfac[N-1] = inv(fac[N-1]);
//    for(int i = N-2; i >= 0; i--){
//        invfac[i] = (invfac[i+1] * (i+1))%md;
//    }
//    return;
//}
//
//int C(int n,int k){
//    if(k > n)
//        return 0;
//    return fac[n] * invfac[k] % md * invfac[n-k] % md;
//}
//
//int A(int n,int k){
//    if(k > n)
//        return 0;
//    return fac[n] * invfac[n-k] % md;
//

int t[2][4*N];
int a[2][N];
void build(int v,int l,int r){
    if(l == r){
        for(int i = 0; i < 2; i++)
        t[i][v] = a[i][l];
        return;
    }
    int m = (l+r)>>1;
    build(v<<1,l,m);
    build(v<<1|1,m+1,r);
    for(int i = 0; i < 2; i++)
    t[i][v] = min(t[i][v<<1],t[i][v<<1|1]);
    return;
}

int get(int v,int l,int r,int tl,int tr,int T){
    if(l > r || tl > tr)
        return INF;
    if(l == tl && r == tr)
        return t[T][v];
    int m = (l+r)>>1;
    return min(get(v<<1,l,m,tl,min(tr,m),T),get(v<<1|1,m+1,r,max(tl,m+1),tr,T));
}
int b[N];

void solve(){
    int n;
    cin >> n;

    string s;
    cin >> s;

    s = "#" + s;
    for(int i = 1; i <= n; i++){
        b[i] = (s[i] == 'T' ? -1 : 1);
    }
    for(int i = 1; i <= n; i++){
        a[0][i] = a[0][i-1] + (s[i] == 'T' ? -1 : 1);
    }
    for(int i = n; i > 0; i--){
        a[1][i] = a[1][i+1] + (s[i] == 'T' ? -1 : 1);
    }
//    for(int i = 1; i <= n; i++){
//        cout << a[i] << " ";
//    }
//    cout << "\n";
    build(1,1,n);

    int q;
    cin >> q;
    while(q--){
        int l,r;
        cin >> l >> r;
        int mn = INF;
        int pos = 0;
        int sum = 0;
        for(int i = l; i <= r; i++){
            sum += b[i];
            if(a[0][i] < mn){
                mn = a[0][i];
                pos = i;
            }
        }
        mn -= a[0][l-1];
        mn = -mn;
        int cnt = 0;
        vector<int> S;
        for(int i = l; i <= r && mn > 0; i++){
            if(b[i] == -1){
                cnt++;
                S.pb(i);
                b[i] = 0;
                mn--;
            }
        }
        mn = INF;
        pos = -1;
        sum = 0;
        for(int i = r; i >= l; i--){
            sum += b[i];
            if(sum < mn){
                mn = sum;
                pos = i;
            }
        }
        mn = -mn;
        cnt += max(0ll,mn);
        for(auto& x : S)
            b[x] = -1;
        cout << cnt << "\n";
    }

    return;
}

signed main(){
    ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
    int tests = 1;
//    cin >> tests;
    for(int test = 1; test <= tests; test++){
//        cerr << "test = " << test << "\n";
        solve();
    }
    return 0;
}
/**
x2 x1 x0

[x2+2*x1+x0] [x1+x0] [x0]

1 0 0
2 1 0
1 1 1

1 0 0
-2 1 0
1 -1 1

**/

Compilation message (stderr)

election.cpp: In function 'void solve()':
election.cpp:134:13: warning: variable 'pos' set but not used [-Wunused-but-set-variable]
  134 |         int pos = 0;
      |             ^~~

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