Submission #867984

#	Time	Username	Problem	Language	Result	Execution time	Memory
867984		guagua0407	절취선 (JOI14_ho_t5)	C++17	0 / 100	1 ms	600 KiB

2014_ho_t5

//#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=1e5+5;
int bit[mxn];
int a[mxn];
vector<int> st;
int ans=0;
int L,R;
int n;

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

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

void init(){
    for(int i=0;i<n;i++){
        update(a[i],1);
    }
}

void upd(int l,int r){
    while(L>l){
        L--;
        update(a[L],1);
    }
    while(R<r){
        R++;
        update(a[R],1);
    }
    while(L<l){
        update(a[L],-1);
        L++;
    }
    while(R>r){
        update(a[R],-1);
        R--;
    }
}

void go(int l,int r,int tl,int tr){
    if(l>r or tl>tr){
        return;
    }
    int mid=(l+r)/2;
    int mx=-1e9;
    int node=max(tl,st[mid]);
    for(int i=max(tl,st[mid]);i<=tr;i++){
        upd(st[mid],i);
        int val=query(a[st[mid]]-1)-query(a[i]);
        if(val>mx){
            mx=val;
            node=i;
        }
    }
    ans=max(ans,mx);
    go(mid+1,r,node,tr);
    go(l,mid-1,tl,node);
}


int main() {_
    cin>>n;
    map<int,int> mp;
    for(int i=0;i<n;i++){
        cin>>a[i];
        mp[a[i]]++;
    }
    ll cnt=1;
    for(auto &v:mp){
        v.s=cnt++;
    }
    for(int i=0;i<n;i++){
        a[i]=mp[a[i]];
    }
    cnt=0;
    for(int i=0;i<n;i++){
        for(int j=0;j<i;j++){
            cnt+=(a[i]<a[j]);
        }
    }
    if(cnt==0){
        cout<<1<<'\n';
        return 0;
    }
    L=0,R=n-1;
    init();
    for(int i=0;i<n;i++){
        if(st.empty() or a[st.back()]<a[i]){
            st.push_back(i);
        }
    }
    go(0,(int)st.size()-1,0,n-1);
    cout<<max(0ll,cnt-(2*ans+1))<<'\n';
    return 0;
}
//maybe its multiset not set

Compilation message (stderr)

2014_ho_t5.cpp: In function 'void setIO(std::string)':
2014_ho_t5.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);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2014_ho_t5.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: 0 / 5
• Subtask 2: 0 / 5
• Subtask 3: 0 / 20
• Subtask 4: 0 / 20
• Subtask 5: 0 / 50