Submission #1074272

#	Time	Username	Problem	Language	Result	Execution time	Memory
1074272		anango	Longest Trip (IOI23_longesttrip)	C++17	100 / 100	16 ms	704 KiB

longesttrip

#include "longesttrip.h"
#include <bits/stdc++.h>
using namespace std;

int n;
bool are_connected_valid(vector<int> S, vector<int> T) {
    sort(S.begin(), S.end());
    sort(T.begin(), T.end());
    //assert(S.size()>0);
    //assert(T.size()>0);
    /*cout << "QUERYING " << endl;
    for (auto i:S) {
        cout << i <<" ";
    }
    cout << endl;
    for (auto i:T) {
        cout << i <<" ";
    }
    cout << endl;*/
    if (S.size()==0 || T.size()==0) {
        return 0;
    }
    return are_connected(S,T);
}

vector<int> longest_trip(int N, int D) {
    n=N;
    deque<int> path1;
    deque<int> path2;
    path1.push_back(0);
    path2.push_back(1);
    for (int i=2; i<n; i++) {
        if (i<n-2) {
            //merge two at a time
            int C = i;
            int D = i+1;
            int A = path1.back();
            int B = path2.back();
            bool ans1 = are_connected_valid({C},{D});
            bool ans2 = are_connected_valid({C},{A});
            bool ans3 = are_connected_valid({C},{B});
            if (ans1) {
                if (ans2) {
                    //connect both to A
                    path1.push_back(C);
                    path1.push_back(D);
                }
                else if (ans3) {
                    path2.push_back(C);
                    path2.push_back(D);
                }
                else {
                    //conglomerate the paths as we know A-B
                    while (path2.size()) {
                        path1.push_back(path2.back());
                        path2.pop_back();
                    }
                    path2={C,D};
                }
            }
            else {
                if (ans2 && ans3) {
                    //conglomerate C
                    path1.push_back(C);
                    while (path2.size()) {
                        path1.push_back(path2.back());
                        path2.pop_back();
                    }
                    path2={D};
                }
                else if ((!ans2) && (!ans3)) {
                    path1.push_back(D);
                    while (path2.size()) {
                        path1.push_back(path2.back());
                        path2.pop_back();
                    }
                    path2={C};
                }
                else {
                    if (ans2) {
                        path1.push_back(C);
                        path2.push_back(D);
                    }
                    else if (ans3) {
                        path1.push_back(D);
                        path2.push_back(C);
                    }
                    else {
                        assert(false);
                    }
                }
            }
            i++;
            continue;
        }
        //cout << "MEGABLOAT " << i << " " << path1.back() <<" " << path2.back() << endl;
        if (are_connected_valid({path1.back()},{i})) {
            path1.push_back(i);
        }
        else if (are_connected_valid({path2.back()},{i})) {
            path2.push_back(i);
        }
        else {
            //path1's end is connected to path2's end
            while (path2.size()) {
                path1.push_back(path2.back());
                path2.pop_back();
            }
            path2={i};
        }
    }
    vector<int> grp1(path1.begin(), path1.end());
    vector<int> grp2(path2.begin(), path2.end());
    //cout << "JAMBLOAT" <<  " " << grp1.size() <<" " << grp2.size() << endl;
    if (grp1.size()<grp2.size()) {
        swap(grp1,grp2);
    }
    if (grp1.size()==0 || grp2.size()==0 || !are_connected_valid(grp1,grp2)) {
        return grp1;
    }
    vector<int> end1 = {grp1.front(), grp1.back()};
    vector<int> end2 = {grp2.front(), grp2.back()};
    end1.erase(unique(end1.begin(), end1.end()),end1.end());
    end2.erase(unique(end2.begin(), end2.end()),end2.end());
    if (are_connected_valid(end1,end2)) {
        if (are_connected_valid({grp1.front()},{grp2.front()})) {
            vector<int> con;
            for (auto i:grp1) {
                con.push_back(i);
            }
            reverse(con.begin(), con.end());
            for (auto i:grp2) {
                con.push_back(i);
            }
            return con; //length n
        }
        if (are_connected_valid({grp1.front()},{grp2.back()})) {
            vector<int> con;
            for (auto i:grp1) {
                con.push_back(i);
            }
            reverse(con.begin(), con.end());
            reverse(grp2.begin(), grp2.end());
            for (auto i:grp2) {
                con.push_back(i);
            }
            return con; //length n
        }
        if (are_connected_valid({grp1.back()},{grp2.front()})) {
            vector<int> con;
            for (auto i:grp1) {
                con.push_back(i);
            }
            for (auto i:grp2) {
                con.push_back(i);
            }
            return con; //length n
        }
        if (are_connected_valid({grp1.back()},{grp2.back()})) {
            vector<int> con;
            for (auto i:grp1) {
                con.push_back(i);
            }
            reverse(grp2.begin(), grp2.end());
            for (auto i:grp2) {
                con.push_back(i);
            }
            return con; //length n
        }
    }

    int l = 1;
    int r = grp1.size();
    while (l<r) {
        int m = (l+r)/2;
        vector<int> part(grp1.begin(), grp1.begin()+m);
        if (are_connected_valid(part,grp2)) {
            r=m;
        }
        else {
            l=m+1;
        }
    }
    int x1 = l;
    x1--;
    l = 1;
    r = grp2.size();
    while (l<r) {
        int m = (l+r)/2;
        vector<int> part(grp2.begin(), grp2.begin()+m);
        if (are_connected_valid({grp1[x1]},part)) {
            r=m;
        }
        else {
            l=m+1;
        }
    }
    int x2 = l;
    x2--;
    vector<int> ans;
    for (int i=x1+1; i<grp1.size(); i++) {
        ans.push_back(grp1[i]);
    }
    for (int i=0; i<=x1; i++) {
        ans.push_back(grp1[i]);
    }
    for (int i=x2; i<grp2.size(); i++) {
        ans.push_back(grp2[i]);
    } 
    for (int i=0; i<x2; i++) {
        ans.push_back(grp2[i]);
    }

    return ans;
}

Compilation message (stderr)

longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:201:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  201 |     for (int i=x1+1; i<grp1.size(); i++) {
      |                      ~^~~~~~~~~~~~
longesttrip.cpp:207:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  207 |     for (int i=x2; i<grp2.size(); i++) {
      |                    ~^~~~~~~~~~~~

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