Submission #900605

#	Time	Username	Problem	Language	Result	Execution time	Memory
900605		abcvuitunggio	Longest Trip (IOI23_longesttrip)	C++17	100 / 100	10 ms	1012 KiB

longesttrip

#include "longesttrip.h"
#include <bits/stdc++.h>
using namespace std;
vector <int> longest_trip(int N, int D){
    vector <int> a,b;
    int idx[N];
    iota(idx,idx+N,0);
    //shuffle(idx,idx+N,default_random_engine(chrono::steady_clock::now().time_since_epoch().count()));
    a.push_back(idx[0]);
    b.push_back(idx[1]);
    int ch=0;
    for (int j=2;j<N;j++){
        int i=idx[j];
        if (are_connected({a.back()},{i})){
            a.push_back(i);
            ch=0;
            continue;
        }
        if (ch||are_connected({b.back()},{i})){
            b.push_back(i);
            ch=1;
            continue;
        }
        reverse(b.begin(),b.end());
        for (int i:b)
            a.push_back(i);
        b={i};
    }
    if (a.size()<b.size())
        swap(a,b);
    if (!are_connected(a,b))
        return a;
    vector <int> x={0,a.size()-1},y={0,b.size()-1};
    for (int i:x)
        for (int j:y)
            if (are_connected({a[i]},{b[j]})){
                if (!i)
                    reverse(a.begin(),a.end());
                if (j)
                    reverse(b.begin(),b.end());
                for (int k:b)
                    a.push_back(k);
                return a;
            }
    int l=0,r=b.size()-1,i=-1;
    while (l<=r){
        int mid=(l+r)>>1;
        vector <int> tmp;
        for (int i=0;i<=mid;i++)
            tmp.push_back(b[i]);
        if (are_connected(a,tmp)){
            i=mid;
            r=mid-1;
        }
        else
            l=mid+1;
    }
    l=0,r=a.size()-1;
    int j=-1;
    while (l<=r){
        int mid=(l+r)>>1;
        vector <int> tmp;
        for (int i=0;i<=mid;i++)
            tmp.push_back(a[i]);
        if (are_connected(tmp,{b[i]})){
            j=mid;
            r=mid-1;
        }
        else
            l=mid+1;
    }
    vector <int> c;
    for (int k=(j+1)%a.size();c.size()<a.size();k=(k+1)%a.size())
        c.push_back(a[k]);
    for (int k=i;c.size()<a.size()+b.size();k=(k+1)%b.size())
        c.push_back(b[k]);
    return c;
}

Compilation message (stderr)

longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:33:31: warning: narrowing conversion of '(a.std::vector<int>::size() - 1)' from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' [-Wnarrowing]
   33 |     vector <int> x={0,a.size()-1},y={0,b.size()-1};
      |                       ~~~~~~~~^~
longesttrip.cpp:33:31: warning: narrowing conversion of '(a.std::vector<int>::size() - 1)' from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' [-Wnarrowing]
longesttrip.cpp:33:48: warning: narrowing conversion of '(b.std::vector<int>::size() - 1)' from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' [-Wnarrowing]
   33 |     vector <int> x={0,a.size()-1},y={0,b.size()-1};
      |                                        ~~~~~~~~^~
longesttrip.cpp:33:48: warning: narrowing conversion of '(b.std::vector<int>::size() - 1)' from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' [-Wnarrowing]

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