Submission #973679

#	Time	Username	Problem	Language	Result	Execution time	Memory
973679		UltraFalcon	Group Photo (JOI21_ho_t3)	C++17	0 / 100	1 ms	344 KiB

Main

#ifndef DEBUG
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,avx,avx2,abm,mmx,fma,popcnt")
#endif

#include <bits/stdc++.h>
// #define int long long
using ll = long long;

using namespace std;

const int INF = 1e9;

struct Fenwick {
    int n;
    vector<int> b;

    Fenwick(int sz) {
        n = sz+1;
        b.assign(n, 0);
    }

    int query(int k) {
        int res = b[0];
        for (int i=k; i>0; i-=i&-i) {
            res += b[i];
        }
        return res;
    } 

    void update(int k, int x) {
        for (int i=k+1; i<n; i+=i&-i) {
            b[i] += x;
        }
    }
};

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int n; cin >> n;

    vector<int> h(n);
    for (auto &x : h) {
        cin >> x;
        x--;
    }

    vector<int> dp(n, INF);
    for (int i=0; i<n; i++) {
        // precompute stuff
        Fenwick fen(n);
        vector<int> cost(n, 0);
        int cnt1 = 0;
        for (int j=0; j<n; j++) {
            if (h[j] <= i) {
                cost[h[j]] += cnt1;
                // TODO: substract #heights to the left with height h: h[j] < h <= i
                cost[h[j]] -= (j-cnt1) - fen.query(h[j]);
            } else {
                cnt1++;
            }
            fen.update(h[j], +1);
        }
        int cnt2 = 0;
        for (int j=n-1; j>=0; j--) {
            if (h[j] <= i) {
                cost[h[j]] += cnt2;
                cnt2++;
            }
        }
        int tot_cost = 0;
        for (int j=i; j>=0; j--) {
            tot_cost += cost[j];

            if (j > 0) {
                dp[i] = min(dp[i], dp[j-1] + tot_cost);
            } else {
                dp[i] = min(dp[i], tot_cost);
            }
        }
    }

    cout << dp[n-1] << "\n";

}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 7
• Subtask 3: 0 / 32
• Subtask 4: 0 / 20
• Subtask 5: 0 / 36