Submission #803259

#	Time	Username	Problem	Language	Result	Execution time	Memory
803259		guagua0407	Group Photo (JOI21_ho_t3)	C++17	100 / 100	530 ms	564 KiB

Main

//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define f first
#define s second
#define all(x) x.begin(),x.end()
#define _ ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

void setIO(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}

const int mxn=5005;
int pos[mxn];
int num[mxn];
ll dp[mxn];
int bit[2][mxn];

void update(int id,int pos,int val){
    for(;pos<mxn;pos+=(pos&-pos)){
        bit[id][pos]+=val;
    }
}

int query(int id,int pos){
    int ans=0;
    for(;pos;pos-=(pos&-pos)){
        ans+=bit[id][pos];
    }
    return ans;
}

int main() {_
    int n;
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>num[i];
        pos[num[i]]=i;
    }
    for(int i=1;i<=n;i++){
        memset(bit[0],0,sizeof(bit[0]));
        memset(bit[1],0,sizeof(bit[1]));
        ll cur=0;
        dp[i]=(ll)1e18;
        for(int j=n;j>i;j--){
            update(0,pos[j],1);
        }
        for(int j=i;j>=1;j--){
            cur+=query(0,pos[j]);
            cur+=query(1,n)-query(1,pos[j]);
            //cout<<j<<' '<<i<<' '<<cur<<'\n';
            dp[i]=min(dp[i],dp[j-1]+cur);
            update(1,pos[j],1);
        }
    }
    cout<<dp[n]<<'\n';
    return 0;
}
//maybe its multiset not set

Compilation message (stderr)

Main.cpp: In function 'void setIO(std::string)':
Main.cpp:12:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   12 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:13:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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