Submission #1212587

#	Time	Username	Problem	Language	Result	Execution time	Memory
1212587		Aviansh	Longest Trip (IOI23_longesttrip)	C++20	15 / 100	329 ms	472 KiB

longesttrip

#include "longesttrip.h"

#include <bits/stdc++.h>

using namespace std;

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){
        set<int>lef;
        for(int i = 0;i<n;i++){
            lef.insert(i);
        }
        vector<int>ans;
        ans.push_back(0);
        lef.erase(0);
        while(lef.size()>1){
            if(are_connected({ans.back()},{*lef.begin()})){
                ans.push_back(*lef.begin());
                lef.erase(lef.begin());
            }
            else{
                ans.push_back(*(++lef.begin()));
                lef.erase(++lef.begin());
            }
        }
        if(are_connected({*lef.begin()},{ans.back()})){
            ans.push_back(*lef.begin());
            return ans;
        }
        ans.insert(ans.begin(),*lef.begin());
        return ans;
    }
    assert(D==1);
    bool adj[n][n];
    for(int i = 0;i<n;i++){
        fill(adj[i],adj[i]+n,0);
    }
    for(int i = 0;i<n;i++){
        for(int j = i+1;j<n;j++){
            if(are_connected({i},{j})){
                adj[i][j]=adj[j][i]=1;
            }
        }
    }
    vector<int>pt1,pt2;
    pt1.push_back(0);
    for(int i = 1;i<n;i++){
        int prev1 = pt1.back();
        if(adj[prev1][i]){
            pt1.push_back(i);
            continue;
        }
        //not adjacent.
        if(pt2.size()){
            int prev2 = pt2.back();
            if(adj[prev2][i]){
                pt2.push_back(i);
            }
            else{
                assert(adj[prev1][prev2]);
                reverse(pt2.begin(),pt2.end());
                pt1.insert(pt1.end(),pt2.begin(),pt2.end());
                pt2.clear();
                i--;
                continue;
            }
        }
        else{
            pt2.push_back(i);
        }
    }
    int mxi, mxj;
    mxi=-1;
    mxj=-1;
    for(int i = 0;i<pt1.size();i++){
        for(int j = 0;j<pt2.size();j++){
            if(adj[pt1[i]][pt2[j]]){
                if(mxi==-1){
                    mxi=i;
                    mxj=j;
                    continue;
                }
                int ollen = max(mxi+1,(int)pt1.size()-mxi)+max(mxj+1,(int)pt2.size()-mxj);
                int newlen = max(i+1,(int)pt1.size()-i)+max(j+1,(int)pt2.size()-j);
                if(newlen>ollen){
                    mxi=i;
                    mxj=j;
                }
            }
        }
    }
    if(mxi==-1){
        if(pt1.size()>pt2.size()){
            return pt1;
        }
        return pt2;
    }
    vector<int>ans;
    if(mxi+1>pt1.size()-mxi){
        for(int i = 0;i<=mxi;i++){
            ans.push_back(pt1[i]);
        }
    }
    else{
        for(int i = pt1.size()-1;i>=mxi;i--){
            ans.push_back(pt1[i]);
        }
    }
    if(mxj+1>pt2.size()-mxj){
        for(int i = 0;i<=mxj;i++){
            ans.push_back(pt2[i]);
        }
    }
    else{
        for(int i = pt2.size()-1;i>=mxj;i--){
            ans.push_back(pt2[i]);
        }
    }
    return ans;
}

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