Submission #1092693

#	Time	Username	Problem	Language	Result	Execution time	Memory
1092693		alexander707070	Boat (APIO16_boat)	C++14	31 / 100	2090 ms	325180 KiB

boat

#include<bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")

#define MAXN 507
using namespace std;

const long long mod=1e9+7;

int n,a[MAXN],b[MAXN];
vector<int> pos;
map<int,bool> mp;
unordered_map<int,int> where;

pair<int,int> s[MAXN];

long long dp[2][1000007];
long long pref[2][1000007];

long long sum(int id,int from,int to){
    if(from>to)return 0;

    if(from>0)return (pref[id][to]-pref[id][from-1]);
    return pref[id][to];
}

int main(){

    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>a[i]>>b[i];

        for(int f=a[i];f<=b[i];f++){
            if(mp[f])continue;

            mp[f]=true;
            pos.push_back(f);
        }
    }

    pos.push_back(0);
    sort(pos.begin(),pos.end());

    for(int i=0;i<pos.size();i++)where[pos[i]]=i;

    for(int i=1;i<=n;i++){
        s[i]={where[a[i]],where[b[i]]};
    }

    for(int i=0;i<pos.size();i++){
        pref[0][i]=i+1; dp[0][i]=1;
    }

    for(int i=1;i<=n;i++){
        for(int f=0;f<pos.size();f++){

            dp[i%2][f]=(sum(1-i%2,s[i].first-1,min(f,s[i].second)-1) + dp[1-i%2][f])%mod; 

            pref[i%2][f]=dp[i%2][f];
            if(f>0)pref[i%2][f]+=pref[i%2][f-1];
        }
    }

    cout<<dp[n%2][pos.size()-1]-1<<"\n";
 
    return 0;
}

Compilation message (stderr)

boat.cpp: In function 'int main()':
boat.cpp:48:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   48 |     for(int i=0;i<pos.size();i++)where[pos[i]]=i;
      |                 ~^~~~~~~~~~~
boat.cpp:54:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |     for(int i=0;i<pos.size();i++){
      |                 ~^~~~~~~~~~~
boat.cpp:59:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   59 |         for(int f=0;f<pos.size();f++){
      |                     ~^~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 22 / 22
• Subtask 3: 0 / 27
• Subtask 4: 0 / 42