Submission #1023869

#	Time	Username	Problem	Language	Result	Execution time	Memory
1023869		underwaterkillerwhale	Group Photo (JOI21_ho_t3)	C++17	100 / 100	358 ms	165380 KiB

Main

#include <bits/stdc++.h>
#define se              second
#define fs              first
#define pb              push_back
#define ll              long long
#define ii              pair<ll,ll>
#define ld              long double
#define SZ(v)           (int)v.size()
#define ALL(v)          v.begin(), v.end()
#define bit(msk, i)     ((msk >> i) & 1)
#define iter(id, v)     for(auto id : v)
#define rep(i,m,n)      for(int i=(m); i<=(n); i++)
#define reb(i,m,n)      for(int i=(m); i>=(n); i--)

using namespace std;

mt19937_64 rd(chrono :: steady_clock :: now().time_since_epoch().count());
ll Rand(ll l, ll r) { return uniform_int_distribution<ll> (l, r)(rd); }

const int N = 5e3 + 7;
const ll Mod = 1e9 + 7;
const int szBL = 916;
const ll INF = 1e9;
const int BASE = 137;

int n, Q;
int a[N];
int pos[N];
int cnt[N][N], cost[N][N];
int dp[N];

void solution () {
    cin >> n;
    rep (i, 1, n) {
        cin >> a[i];
        pos[a[i]] = i;
    }
    rep (i, 1, n) {
        rep (j, 1, n) {
            cnt[i][j] = cnt[i - 1][j] + (a[i] >= j);
        }
    }
    rep (i, 1, n)
    rep (j, i, n) {
        cost[i][j] = cost[i][j - 1] + cnt[pos[j]][i] - cnt[pos[j]][j];
    }
    memset(dp, 0x3f, sizeof dp);
    dp[0] = 0;
    rep (i, 1, n) {
        int curcost = 0;
        reb (j, i, 1) {
            curcost += cnt[pos[j]][i + 1];
            dp[i]= min(dp[i], dp[j - 1] + curcost + cost[j][i]);
        }
    }
    cout << dp[n] <<"\n";
}



#define file(name) freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout);

int main () {
//    file("c");
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    ll num_Test = 1;
//    cin >> num_Test;
    while(num_Test--)
        solution();
}
/*

*/

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