Submission #447807

#	Time	Username	Problem	Language	Result	Execution time	Memory
447807		cpp219	Group Photo (JOI21_ho_t3)	C++14	100 / 100	286 ms	67400 KiB

Main

#pragma GCC optimization O2
#pragma GCC optimization "unroll-loop"
#pragma target ("avx2")

#include <bits/stdc++.h>
#define ll int
#define ld long double
#define fs first
#define sc second
using namespace std;
typedef pair<ll,ll> LL;
const ll N = 5e3 + 9;
const ll Log2 = 21;
const ll inf = 1e9 + 7;

ll n,a[N],pos[N],inv[N][N],dp[N];

int main(){
    ios_base::sync_with_stdio(NULL); cin.tie(0); cout.tie(0);
    #define task "tst"
    if (fopen(task".INP","r")){
        freopen(task".INP","r",stdin);
        //freopen(task".OUT","w",stdout);
    }
    cin>>n;
    for (ll i = 1;i <= n;i++) cin>>a[i],pos[a[i]] = i;
    for (ll j = 2;j <= n;j++){
        ll now = 0;
        for (ll i = j - 1;i;i--){
            now += (pos[i] > pos[j]);
            inv[i][j] = inv[i][j - 1] + now;
        }
    }
    for (ll i = 1;i <= n;i++){
        dp[i] = inf;
        for (ll j = i - 1;j >= 0;j--)
            dp[i] = min(dp[i], dp[j] + inv[1][i] - inv[1][j] + ((i - j)*(i - j - 1))/2 - 2 * inv[j + 1][i]);
    }
    cout<<dp[n];
}

Compilation message (stderr)

Main.cpp:1: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    1 | #pragma GCC optimization O2
      | 
Main.cpp:2: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    2 | #pragma GCC optimization "unroll-loop"
      | 
Main.cpp:3: warning: ignoring '#pragma target ' [-Wunknown-pragmas]
    3 | #pragma target ("avx2")
      | 
Main.cpp: In function 'int main()':
Main.cpp:22:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   22 |         freopen(task".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

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