# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
1074210 | anango | Longest Trip (IOI23_longesttrip) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#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);
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 (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 = 0;
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;
l = 0;
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;
//assert(are_connected_valid({x1},{x2}));
//assert(x1!=0 && x2!=0 && x1+1!=grp1.size() && x2+1!=grp2.size());
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]);
}
assert(ans.size()==n && grp1.size()+grp2.size()==n);
for (int i=0; i<n-1; i++) {
assert(are_connected_valid({ans[i],ans[i+1]}));
}
return ans;
}