Submission #1092300

#	Time	Username	Problem	Language	Result	Execution time	Memory
1092300		PagodePaiva	Group Photo (JOI21_ho_t3)	C++17	100 / 100	1696 ms	756 KiB

Main

#include<bits/stdc++.h>

using namespace std;

const int N = 5010;
int n;
int v[N];
int dp[N];

struct Segtree{
    int tree[4*N];
    int join(int a, int b){
        return a+b;
    }
    void build(int node, int l, int r){
        if(l == r){
            tree[node] = 0;
            return;
        }
        int mid = (l+r)/2;
        build(2*node, l, mid);
        build(2*node+1, mid+1, r);
        tree[node] = join(tree[2*node], tree[2*node+1]);
        return;
    }
    void update(int node, int l, int r, int pos, int val){
        if(l == r){
            tree[node] = val;
            return;
        }
        int mid = (l+r)/2;
        if(l <= pos and pos <= mid) update(2*node, l, mid, pos, val);
        else update(2*node+1, mid+1,r, pos, val);
        tree[node] = join(tree[2*node], tree[2*node+1]);
        return;
    }
    int query(int node, int l, int r, int tl, int tr){
        if(l > r) return 0;
        if(l <= tl and tr <= r) return tree[node];
        if(l > tr or tl > r) return 0;
        int mid = (tl+tr)/2;
        return join(query(2*node, l, r, tl, mid), query(2*node+1, l, r, mid+1, tr));
    }
} seg;

int p[N];

void solve(int t){
    vector <int> atual;
    for(int i = 1;i <= n;i++){
        if(v[i] <= t) atual.push_back(v[i]);
    }
    for(int i = 1;i <= t;i++){
        p[atual[i-1]] = i;
    }
    seg.build(1, 1, t);
    int sum = 0;
    dp[t] = 1e8;
    for(int i = t;i > 0;i--){
        sum += t - p[i];
        sum -= seg.query(1, 1, p[i]-1, 1, t);
        seg.update(1, 1, t, p[i], 1);
        dp[t] = min(dp[t], dp[i-1] + sum);
    }
    return;
}

int main(){
    cin >> n;
    for(int i = 1;i <= n;i++){
        cin >> v[i];
    }
    dp[0] = 0;
    for(int i = 1;i <= n;i++){
        solve(i);
    }
    cout << dp[n] << '\n';
}

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