Submission #1832333

---

Source Code Expand

#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <sstream>
#include <functional>
#include <map>
#include <string>
#include <cstring>
#include <vector>
#include <queue>
#include <stack>
#include <deque>
#include <set>
#include <list>
#include <numeric>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> P;
const double PI = 3.14159265358979323846;
const double EPS = 1e-12;
const ll INF = 1LL<<29;
const ll mod = 1e9+7;
#define rep(i,n) for(int (i)=0;(i)<(ll)(n);++(i))
#define repd(i,n,d) for(ll (i)=0;(i)<(ll)(n);(i)+=(d))
#define all(v) (v).begin(), (v).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset((m),(v),sizeof(m))
#define chmin(X,Y) ((X)>(Y)?X=(Y),true:false)
#define chmax(X,Y) ((X)<(Y)?X=(Y),true:false)
#define fst first
#define snd second
#define UNIQUE(x) (x).erase(unique(all(x)),(x).end())
template<class T> ostream &operator<<(ostream &os, const vector<T> &v){int n=v.size();rep(i,n)os<<v[i]<<(i==n-1?"":" ");return os;}

#define N 10010
int n, x[2][N], s[N], d;
P xx[2][N];

int bfs(int p0){
	queue<int> q;
	q.push(p0);
	int cnt = 0;
	while(!q.empty()){
		int p = q.front(); q.pop();
		int t = x[s[p]][p];
		rep(i, 2){
			P *l = lower_bound(xx[i], xx[i]+n, P(t-d+1, 0));
			P *r = upper_bound(xx[i], xx[i]+n, P(t+d-1, n));
			//cerr<<(r-l)<<endl;
			while(l<r){
				if(l->snd!=p){
					if(s[l->snd]==i) return -1;
					if(s[l->snd]==-1){
						s[l->snd] = !i;
						cnt++;
						q.push(l->snd);
					}
				}
				l++;
			}
		}
	}
	//cerr<<d<<" "<<p0<<" "<<cnt<<endl;
	return cnt;
}

bool dfs(int p){
	while(p<n && s[p]>=0) p++;
	if(p>=n) return true;
	int s2[N];
	memcpy(s2, s, sizeof(s));
	s[p] = 0;
	int cnt = bfs(p);
	if(cnt==0) return dfs(p+1);
	if(cnt>0 && dfs(p+1)) return true;
	memcpy(s, s2, sizeof(s));
	s[p] = 1;
	if(bfs(p)>=0) return dfs(p+1);
	memcpy(s, s2, sizeof(s));
	s[p] = -1;
	return false;
}

bool solve(){
	mset(s, -1);
	return dfs(0);
}

int main(){
	cin>>n;
	rep(i, n) cin>>x[0][i]>>x[1][i];
	rep(i, n) if(rand()%2) swap(x[0][i], x[1][i]);
	rep(j, 2){
		rep(i, n){
			xx[j][i] = P(x[j][i], i);
		}
		sort(xx[j], xx[j]+n);
	}
	int lb = 0, ub = 1e9/(n-1)+1;
	while(ub-lb>1){
		d = (lb+ub)/2;
		(solve()?lb:ub)=d;
	}
	cout<<lb<<endl;
	return 0;
}

Submission Info

Judge Result