Submission #736171

#	Time	Username	Problem	Language	Result	Execution time	Memory
736171		ksu2009en	Event Hopping (BOI22_events)	C++14	10 / 100	272 ms	65720 KiB

events

#include <iostream>
#include <vector>
#include <string>
#include <math.h>
#include <cmath>
#include <iomanip>
#include <cstdio>
#include <algorithm>
#include <numeric>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <deque>
#include <bitset>
#include <cstring>
#include <unordered_map>

using namespace std;
typedef long long ll;

struct one{
    ll first, second, ind;
};

bool cmp(one p1, one p2){
    if(p1.second == p2.second)
        return p1.first < p2.first;
    return p1.second < p2.second;
}

void compress(vector<one> &a){
    vector<ll>b;
    for(auto i: a){
        b.push_back(i.first);
        b.push_back(i.second);
    }
    
    sort(b.begin(), b.end());
    b.resize(unique(b.begin(), b.end()) - b.begin());
    
    ll step = 1;
    map<ll, ll> mp;
    for(auto i: b)
        mp[i] = step++;
    
    for(auto &i: a){
        i.first = mp[i.first];
        i.second = mp[i.second];
    }
}

ll dp[5007][5007];
vector<ll>start_here[5007];

vector<one>a;

void count_dp(one fin){
    for(int i = 0; i < a.size(); i++)
        dp[i][fin.ind] = 1e9;
    
    dp[fin.ind][fin.ind] = 0;
    
    bool ok = false;
    
    multiset<ll>st;
    
    for(int ind = a.size() - 1; ind >= 0; ind--){
        auto i = a[ind];
        
        if(i.ind == fin.ind){
            //cout << i.ind << ' ' << ind << endl;
            ok = true;
            st.insert(0);
        }
        else if(ok){
            if(st.empty()){
               // cout << "st.empty() " << i.ind << endl;
                dp[i.ind][fin.ind] = 1e9;
                st.insert(1e9);
            }
            else{
              //  cout << i.ind << endl;
              //  for(auto j: st)
              //      cout << j << ' ';
              //  cout << endl;
                dp[i.ind][fin.ind] = *st.begin();
                if(*st.begin() != (ll)(1e9))
                    dp[i.ind][fin.ind]++;
                                
                st.insert(dp[i.ind][fin.ind]);
            }
        }
        else{
           // cout << "not yet " << i.ind << endl;
            st.insert(1e9);
        }
        
        if(ind - 1 >= 0){
            for(int del = i.second; del > a[ind - 1].second; del--)
                for(auto j: start_here[del]){
                    st.erase(st.find(dp[j][fin.ind]));
                }
        }
    }
}

vector<ll>count_dp2(ll start){
    vector<ll>dp2(a.size(), 1e9);
    
    dp2[start] = 0;
    
    for(auto i: a){
        for(auto j: a){
            if(i.first <= j.second && j.second <= i.second){
                dp2[i.ind] = min(dp2[i.ind], dp2[j.ind] + 1);
            }
        }
    }
    
    return dp2;
}

int main(){
    srand(time(0));
    ll n, q;
    cin >> n >> q;
    
    a.resize(n);
    for(int i = 0; i < n; i++){
        cin >> a[i].first >> a[i].second;
        a[i].ind = i;
    }
    
    compress(a);
    sort(a.begin(), a.end(), cmp);

    
    for(auto i: a)
        start_here[i.first].push_back(i.ind);
    
    for(auto i: a){
        count_dp(i);
    }
   
    while(q--){
        ll l, r;
        cin >> l >> r;
        //l = 1 + rand() % n, r = 1 + rand() % n;
        
        l--, r--;
        
        //auto dp2 = count_dp2(l);
        
        if(dp[l][r] == (ll)(1e9))
            cout << "impossible" << endl;
        else{
            cout << dp[l][r] << endl;
        }
    }
     
    return 0;
}
/*
 8 1
 1 2
 3 4
 1 5
 6 7
 5 10
 10 20
 15 20
 999999999 1000000000
 1 7
 
 
 */
/*
 1 2
 1 1000000000
 
 */
/*
 5 9
 2 0
 
 */
/*
 10 100
 1 3
 4 6
 2 8
 8 23
 1 4
 2 4
 6 73
 2 34
 1 9
 8 90
 
 2 3
 
 
 */

Compilation message (stderr)

events.cpp: In function 'void count_dp(one)':
events.cpp:59:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<one>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   59 |     for(int i = 0; i < a.size(); i++)
      |                    ~~^~~~~~~~~~

• Subtask 1: 0 / 10
• Subtask 2: 10 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30