Submission #643615

#	Time	Username	Problem	Language	Result	Execution time	Memory
643615		maomao90	Monochrome Points (JOI20_monochrome)	C++17	4 / 100	9 ms	468 KiB

monochrome

// Hallelujah, praise the one who set me free
// Hallelujah, death has lost its grip on me
// You have broken every chain, There's salvation in your name
// Jesus Christ, my living hope
#include <bits/stdc++.h> 
using namespace std;

#define REP(i, s, e) for (int i = (s); i < (e); i++)
#define RREP(i, s, e) for (int i = (s); i >= (e); i--)
template <class T>
inline bool mnto(T& a, T b) {return a > b ? a = b, 1 : 0;}
template <class T>
inline bool mxto(T& a, T b) {return a < b ? a = b, 1: 0;}
typedef long long ll;
typedef long double ld;
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
typedef tuple<int, int, int> iii;
#define ALL(_a) _a.begin(), _a.end()
#define SZ(_a) (int) _a.size()
#define pb push_back
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
typedef vector<iii> viii;

#ifndef DEBUG
#define cerr if (0) cerr
#endif

const int INF = 1000000005;
const ll LINF = 1000000000000000005ll;
const int MAXN = 400005;

int n;
string s;
ll ans;

int fw[MAXN];
void incre(int i, int x) {
    for (; i <= 2 * n; i += i & -i) {
        fw[i] += x;
    }
}
int qsm(int i) {
    int res = 0;
    for (; i > 0; i -= i & -i) {
        res += fw[i];
    }
    return res;
}
int qsm(int s, int e) {
    return qsm(e) - qsm(s - 1);
}

int main() {
#ifndef DEBUG
    ios::sync_with_stdio(0), cin.tie(0);
#endif
    cin >> n;
    cin >> s;
    s = "?" + s;
    vll vec;
    REP (i, 2, 2 * n + 1) {
        if (s[i] == s[1]) {
            continue;
        }
        int u = 1, v = i;
        vii eg;
        cerr << u << ' ' << v << '\n';
        while (u <= 2 * n) {
            eg.pb({u, v});
            cerr << ' ' << u << ' ' << v << '\n';
            u++; v++;
            while (u <= 2 * n && s[u] != s[1]) {
                u++;
            }
            if (v > 2 * n) {
                v -= 2 * n;
            }
            while (s[v] == s[1]) {
                v++;
                if (v > 2 * n) {
                    v -= 2 * n;
                }
            }
        }
        assert(SZ(eg) == n);
        for (auto &[u, v] : eg) {
            if (u > v) {
                swap(u, v);
            }
        }
        sort(ALL(eg));
        REP (i, 1, 2 * n + 1) {
            fw[i] = 0;
        }
        ll sm = 0;
        for (auto [u, v] : eg) {
            sm += qsm(u, v);
            incre(v, 1);
        }
        mxto(ans, sm);
        cerr << ' ' << sm << '\n';
        vec.pb(sm);
    }
    bool dec = 0;
    bool can = 1;
    REP (i, 1, SZ(vec)) {
        //assert(vec[i] != vec[i - 1]);
        if (vec[i] < vec[i - 1]) {
            dec = 1;
        } else if (dec) {
            can = 0;
            break;
        }
    }
    bool can2 = 1;
    dec = 0;
    REP (i, 1, SZ(vec)) {
        //assert(vec[i] != vec[i - 1]);
        if (vec[i] > vec[i - 1]) {
            dec = 1;
        } else if (dec) {
            can2 = 0;
            break;
        }
    }
    assert(can || can2);
    cout << ans << '\n';
    return 0;
}

• Subtask 1: 4 / 4
• Subtask 2: 0 / 21
• Subtask 3: 0 / 10
• Subtask 4: 0 / 65