Submission #1136268

#	Time	Username	Problem	Language	Result	Execution time	Memory
1136268		pan	Group Photo (JOI21_ho_t3)	C++20	100 / 100	670 ms	392448 KiB

Main

#include <bits/stdc++.h>
//#include "includeall.h"
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
#define endl '\n'
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define lb lower_bound
#define ub upper_bound
#define input(x) scanf("%lld", &x);
#define input2(x, y) scanf("%lld%lld", &x, &y);
#define input3(x, y, z) scanf("%lld%lld%lld", &x, &y, &z);
#define input4(x, y, z, a) scanf("%lld%lld%lld%lld", &x, &y, &z, &a);
#define print(x, y) printf("%lld%c", x, y);
#define show(x) cerr << #x << " is " << x << endl;
#define show2(x,y) cerr << #x << " is " << x << " " << #y << " is " << y << endl;
#define show3(x,y,z) cerr << #x << " is " << x << " " << #y << " is " << y << " " << #z << " is " << z << endl;
#define all(x) x.begin(), x.end()
#define discretize(x) sort(x.begin(), x.end()); x.erase(unique(x.begin(), x.end()), x.end());
#define FOR(i, x, n) for (ll i =x; i<=n; ++i) 
#define RFOR(i, x, n) for (ll i =x; i>=n; --i) 
using namespace std;
mt19937_64 rnd(chrono::steady_clock::now().time_since_epoch().count());
//using namespace __gnu_pbds;
//#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
//#define ordered_multiset tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update>
typedef long long ll;
typedef long double ld;
typedef pair<ld, ll> pd;
typedef pair<string, ll> psl;
typedef pair<ll, ll> pi;
typedef pair<ll, pi> pii;
typedef pair<pi, pi> piii;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

ll h[5005];
ll inv1[5005][5005]; // inv1[a][b] = no. of b >= i > a such that pos[i] > pos[a]
ll inv2[5005][5005]; // inv2[a][b] = no. of i >= b such that pos[i] < pos[a]
ll dp[5005];

int main()
{
	ll n;
	cin >> n;
	for (ll i=0; i<=n+1; ++i) for (ll j=0; j<=n+1; ++j) inv1[i][j] = inv2[i][j] = dp[i] = 0;
	for (ll i=1; i<=n; ++i) cin >> h[i];
	for (ll i=1; i<=n; ++i) for (ll j=i+1; j<=n; ++j) // cal inv2
	{
		if (h[i] > h[j]) inv2[h[j]][h[i]]++;
	}
	for (ll i=1; i<=n; ++i) for (ll j=i-1; j>=1; --j) // cal inv2
	{
		if (h[i] > h[j]) inv1[h[j]][h[i]]++;
	}
	for (ll i=1; i<=n; ++i) for (ll j=1; j<=n; ++j) inv1[i][j] += inv1[i][j-1];
	for (ll i=1; i<=n; ++i) for (ll j=n; j>=1; --j   ) inv2[i][j] += inv2[i][j+1];
	// dp
	dp[0] = 0;
	for (ll i=1; i<=n; ++i)
	{
		dp[i] = 1e15;
		ll ps = 0;
		for (ll j=i; j>0; --j)
		{
			ps += inv2[j][i+1] + inv1[j][i];
			dp[i] = min(dp[i], dp[j-1] + ps);
		}
	}
	cout << dp[n] << endl;
	
    return 0;
}

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