Submission #877096

#	Time	Username	Problem	Language	Result	Execution time	Memory
877096		SorahISA	Chorus (JOI23_chorus)	C++17	61 / 100	2073 ms	1048576 KiB

chorus

#ifndef SorahISA
#define SorahISA
#include SorahISA __FILE__ SorahISA

struct BIT {
    int maxn;
    vector<int> bit;
    
    BIT() {}
    BIT(int N) {init(N);}
    
    void init(int N) {
        maxn = 1 << (__lg(N) + 1);
        bit.assign(maxn, 0);
    }
    
    int query(int L, int R) {return _query(R) - _query(L-1);}
    int _query(int idx, int ans = 0) {
        while (idx) ans += bit[idx], idx -= idx & -idx;
        return ans;
    }
    
    void add(int idx, int val) {
        while (idx < maxn) bit[idx] += val, idx += idx & -idx;
    }
};

void solve() {
    int N, K; cin >> N >> K;
    string S; cin >> S;
    
    vector<int> A(N+1, 0), B(N+1, 0); /// 1-based
    for (int i = 0, cA = 0, cB = 0; i < 2*N; ++i) {
         if (S[i] == 'A') A[++cA] = i+1;
         if (S[i] == 'B') B[++cB] = i+1;
    }
    // for (int i = 0; i <= N; ++i) debug(i, A[i], B[i]);
    
    BIT bitA, bitB;
    vector<vector<int>> inv(N+1, vector<int>(N+1, 0));
    for (int a = 1; a <= N; ++a) {
        bitA.init(2*N), bitB.init(2*N);
        for (int i = N-1; i >= 0; --i) {
            bitB.add(B[i+1], 1);
            if (i < a) {
                inv[i][a] = inv[i+1][a] + bitA.query(B[i+1], 2*N) + bitB.query(1, A[i+1]);
                bitA.add(A[i+1], 1);
            }
        }
    }
    
    vector<vector<int>> dp(N+1, vector<int>(N+1, 4*N*N)); dp[0][0] = 0;
    vector<vector<int>> fr(N+2, vector<int>(N+1, 0));
    for (int k = 1; k <= N; ++k) {
        fr[N+1][k] = N;
        for (int a = N; a >= 1; --a) {
            for (int i = max(int(0), fr[a][k-1]); i <= min(a-1, fr[a+1][k]); ++i) {
                if (chmin(dp[a][k], dp[i][k-1] + inv[i][a])) fr[a][k] = i;
            }
        }
    }
    cout << dp[N][K] << "\n";
}

int32_t main() {
    fastIO();
    
    int t = 1; // cin >> t;
    for (int _ = 1; _ <= t; ++_) {
        solve();
    }
    
    return 0;
}

#else

#ifdef local
#define _GLIBCXX_DEBUG 1
#endif
#pragma GCC optimize("Ofast", "unroll-loops")
#include <bits/stdc++.h>
using namespace std;

#define int int64_t
#define double __float80
using pii = pair<int, int>;
template <typename T> using Prior = std::priority_queue<T>;
template <typename T> using prior = std::priority_queue<T, vector<T>, greater<T>>;

// #define X first
// #define Y second
#define eb emplace_back
#define ef emplace_front
#define ee emplace
#define pb pop_back
#define pf pop_front
#define ALL(x) begin(x), end(x)
#define RALL(x) rbegin(x), rend(x)
#define SZ(x) ((int)(x).size())

#ifdef local
#define fastIO() void()
#define debug(...) \
    fprintf(stderr, "\u001b[33mAt [%s], line %d: (%s) = ", __FUNCTION__, __LINE__, #__VA_ARGS__), \
    _do(__VA_ARGS__), fprintf(stderr, "\u001b[0m")
template <typename T> void _do(T &&_t) {cerr << _t << "\n";}
template <typename T, typename ...U> void _do(T &&_t, U &&..._u) {cerr << _t << ", ", _do(_u...);}
#else
#define fastIO() ios_base::sync_with_stdio(0), cin.tie(0)
#define debug(...) void()
#endif

template <typename T, typename U> bool chmin(T &lhs, U rhs) {return lhs > rhs ? lhs = rhs, 1 : 0;}
template <typename T, typename U> bool chmax(T &lhs, U rhs) {return lhs < rhs ? lhs = rhs, 1 : 0;}

#endif

• Subtask 1: 16 / 16
• Subtask 2: 24 / 24
• Subtask 3: 21 / 21
• Subtask 4: 0 / 26
• Subtask 5: 0 / 13