Submission #1127681

#	Time	Username	Problem	Language	Result	Execution time	Memory
1127681		nguyenkhangninh99	Group Photo (JOI21_ho_t3)	C++20	100 / 100	313 ms	564 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define int long long

const int maxn = 5e3 + 5;
int a[maxn], dp[maxn], pos[maxn];


struct FenwickTree{
    vector<int> tree;
 
    void init(int n){
        tree.assign(n + 2, 0);
    }
 
    void update(int v, int val) {
        for (; v < tree.size(); v += v & (-v)) tree[v] += val;
    }
    
    int get(int v) {
        int res = 0;
        for (; v; v -= v & (-v)) res += tree[v];
        return res;
    }
} bit;

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

    for(int i = 1; i <= n; i++){
        int x; cin >> x;
        pos[x] = i;
        dp[i] = 1e9;
    }

    bit.init(n + 1);
    dp[0] = 0;


    for(int i = 0; i <= n - 1; i++){
        int cost = 0;
        for(int j = i + 1; j <= n; j++){
            int cur = j - i - 1;
            cost += pos[j] - (i + 1) - (cur - bit.get(pos[j]));
            dp[j] = min(dp[j], dp[i] + cost);
            bit.update(pos[j], 1);

        }

        bit.init(n + 1);

        for(int j = 1; j <= n; j++) if(j > i &&  pos[j] < pos[i + 1]) pos[j]++;
    }
    cout << dp[n] << '\n';
}


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

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