Submission #960203

#	Time	Username	Problem	Language	Result	Execution time	Memory
960203		tutis	Longest Trip (IOI23_longesttrip)	C++17	85 / 100	54 ms	1376 KiB

longesttrip

#include "longesttrip.h"
#include <bits/stdc++.h>
using namespace std;
mt19937_64 rng(15645869);
 
std::vector<int> longest_trip(int N, int D)
{
    vector<int>x, y;
    vector<int>p;
    for(int i=0;i<N;i++){
        p.push_back(i);
    }
    bool yes[256][256];
    bool no[256][256];
    for(int i=0;i<256;i++){
        for(int j=0;j<256;j++){
            yes[i][j]=false;
            no[i][j]=false;
        }
    }
    auto conn = [&](vector<int>x,vector<int>y) -> bool {
        int c1=0;
        for(int a: x){
            for(int b: y){
                if(yes[a][b]){
                    return true;
                }
                c1 += no[a][b];
            }
        }
        if(c1==x.size()*y.size()){
            return false;
        }
        bool ans = are_connected(x,y);
        if(!ans){
            for(int a: x){
                for(int b: y){
                    no[a][b]=true;
                    for(int c=0;c<N;c++){
                        if(no[a][c] && c!=a && c!=b){
                            yes[b][c] = true;
                            yes[c][b] = true;
                        }
                        if(no[b][c] && c!=a && c!=b){
                            yes[a][c] = true;
                            yes[c][a] = true;
                        }
                    }
                }
            }
        }
        if(ans && x.size()==1 && y.size()==1){
            yes[x[0]][y[0]]=true;
            yes[y[0]][x[0]]=true;
        }
        return ans;
    };
    auto fix=[&](){
        if(x.size()==0 || y.size()==0){
            return;
        }
        for(int a: x){
            for(int b: x){
                yes[a][b]=yes[b][a]=true;
            }
        }
        for(int a: y){
            for(int b: y){
                yes[a][b]=yes[b][a]=true;
            }
        }
    };
    shuffle(p.begin(),p.end(),rng);
    while(!p.empty()){
        int i=p.back();
        p.pop_back();
        if(x.size()==0){
            x={i};
            continue;
        }
        if(y.size()==0){
            if(conn({i}, {x[0]})){
                x.insert(x.begin(),i);
                continue;
            }
            if (conn({i}, {x.back()})){
                x.push_back(i);
                continue;
            }
            if(!conn({i}, x)){
                y={i};
                fix();
                continue;
            }
            int lo=1;
            int hi=x.size()-2;
            while(lo<hi){
                int m=(lo+hi)/2;
                vector<int>z;
                for(int i=lo;i<=m;i++){
                    z.push_back(x[i]);
                }
                if(conn(z, {i})){
                    hi=m;
                } else{
                    lo=m+1;
                }
            }
            vector<int>z;
            for(int i=lo+1;i<x.size();i++){
                z.push_back(x[i]);
            }
            for(int i=0;i<=lo;i++){
                z.push_back(x[i]);
            }
            z.push_back(i);
            x=z;
            continue;
        }
        if(!conn(x,{i})){
            y.push_back(i);
            fix();
            continue;
        }
        if(!conn(y,{i})){
            x.push_back(i);
            fix();
            continue;
        }
        int i0=0;
        int j0=0;
        if(!conn({x[0]},{i})){
            int lo=1;
            int hi=x.size()-1;
            while(lo<hi){
                int m=(lo+hi)/2;
                vector<int>z;
                for(int i=lo;i<=m;i++){
                    z.push_back(x[i]);
                }
                if(are_connected(z, {i})){
                    hi=m;
                } else{
                    lo=m+1;
                }
            }
            i0=lo;
        } else {
            int lo=0;
            int hi=y.size()-1;
            while(lo<hi){
                int m=(lo+hi)/2;
                vector<int>z;
                for(int i=lo;i<=m;i++){
                    z.push_back(y[i]);
                }
                if(are_connected(z, {i})){
                    hi=m;
                } else{
                    lo=m+1;
                }
            }
            j0=lo;
        }
        swap(x[i0], x.back());
        swap(y[j0], y[0]);
        x.push_back(i);
        for(int i: y){
            x.push_back(i);
        }
        y={};
    }
    if(x.size()>y.size()){
        return x;
    } else{
        return y;
    }
}

Compilation message (stderr)

longesttrip.cpp: In lambda function:
longesttrip.cpp:31:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |         if(c1==x.size()*y.size()){
      |            ~~^~~~~~~~~~~~~~~~~~~
longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:110:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  110 |             for(int i=lo+1;i<x.size();i++){
      |                            ~^~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 25 / 25
• Subtask 4: 45 / 60