Submission #846629

#	Time	Username	Problem	Language	Result	Execution time	Memory
846629		ttamx	Longest Trip (IOI23_longesttrip)	C++17	15 / 100	9 ms	852 KiB

longesttrip

#include "longesttrip.h"
#include<bits/stdc++.h>

using namespace std;

int bsearch(vector<int> vec,vector<int> fixed){
    int l=0,r=vec.size()-1;
    while(l<r){
        int m=(l+r)/2;
        vector<int> res;
        for(int i=l;i<=m;i++)res.emplace_back(vec[i]);
        if(are_connected(res,fixed))r=m;
        else l=m+1;
    }
    return l;
}

vector<int> longest_trip(int N, int D)
{
    if(D==3){
        vector<int> ans(N);
        iota(ans.begin(),ans.end(),0);
        return ans;
    }
    if(D==2){
        deque<int> path;
        for(int i=0;i<3;i++)path.emplace_back(i);
        for(int i=1;i<3;i++){
            if(!are_connected({i-1},{i})){
                swap(path[0],path[i-1]);
                swap(path[2],path[i]);
                break;
            }
        }
        for(int i=3;i<N;i++){
            if(are_connected({i},{path[0]})){
                path.emplace_front(i);
            }else{
                path.emplace_back(i);
            }
        }
        vector<int> ans;
        for(auto x:path)ans.emplace_back(x);
        return ans;
    }
    vector<int> path[2];
    for(int i=0;i<2;i++)path[i].emplace_back(i);
    for(int i=2;i<N;i++){
        if(are_connected({i},{path[0].back()})){
            path[0].emplace_back(i);
            continue;
        }
        if(are_connected({i},{path[1].back()})){
            path[1].emplace_back(i);
            continue;
        }
        while(!path[1].empty()){
            path[0].emplace_back(path[1].back());
            path[1].pop_back();
        }
        path[1].emplace_back(i);
    }
    if(path[0].size()<path[1].size())swap(path[0],path[1]);
    if(!are_connected(path[0],path[1]))return path[0];
    if(are_connected({path[0][0]},{path[1][0]})){
        reverse(path[1].begin(),path[1].end());
        auto ans=path[1];
        for(auto x:path[0])ans.emplace_back(x);
        return ans;
    }
    if(are_connected({path[0][0]},{path[1].back()})){
        auto ans=path[1];
        for(auto x:path[0])ans.emplace_back(x);
        return ans;
    }
    if(are_connected({path[0].back()},{path[1][0]})){
        auto ans=path[0];
        for(auto x:path[1])ans.emplace_back(x);
        return ans;
    }
    if(are_connected({path[0].back()},{path[1].back()})){
        auto ans=path[0];
        reverse(path[1].begin(),path[1].end());
        for(auto x:path[1])ans.emplace_back(x);
        return ans;
    }
    int id0=bsearch(path[0],path[1]);
    int id1=bsearch(path[1],{path[0][id0]});
    vector<int> ans;
    for(int i=0;i<path[0].size();i++)ans.emplace_back((id0+i+1)%path[0].size());
    for(int i=0;i<path[1].size();i++)ans.emplace_back((id1+i)%path[1].size());
    return ans;
}

Compilation message (stderr)

longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:90:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   90 |     for(int i=0;i<path[0].size();i++)ans.emplace_back((id0+i+1)%path[0].size());
      |                 ~^~~~~~~~~~~~~~~
longesttrip.cpp:91:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   91 |     for(int i=0;i<path[1].size();i++)ans.emplace_back((id1+i)%path[1].size());
      |                 ~^~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 0 / 25
• Subtask 4: 0 / 60