Submission #75517

#	Time	Username	Problem	Language	Result	Execution time	Memory
75517		Namnamseo	Highway Tolls (IOI18_highway)	C++17	51 / 100	341 ms	9472 KiB

highway

#include <bits/stdc++.h>
using namespace std;
using ll=long long;
#define pb push_back

#define rep(i,n) for(int i=0; i<(n); ++i)
#define rrep(i,n) for(int i=1; i<=(n); ++i)

ll ask(const vector<int>&);
void answer(int, int);

vector<int> asking;

int n, m;

vector<int> e[90010];
int es[130010];

ll base;

int find_cut(int l, int r){
	if(l == r) return l;
	int mid = (l+r)/2;
	for(int p=l; p<=mid; ++p) for(int ei:e[p]) asking[ei]=1;
	bool res = (ask(asking) > base);
	for(int p=l; p<=mid; ++p) for(int ei:e[p]) asking[ei]=0;
	if(res) return find_cut(l, mid);
	else return find_cut(mid+1, r);
}

int cut;

int dst[90010];
int q[90010], hd, tl;
bool vis[90010];

int find_deep(int l, int r){
	if(l == r){
		return q[l];
	}
	int mid=(l+r)/2;
	for(int i=mid+1; i<=r; ++i) for(int ei:e[q[i]]) asking[ei]=1;
	bool res = (ask(asking) > base);
	for(int i=mid+1; i<=r; ++i) for(int ei:e[q[i]]) asking[ei]=0;
	if(res) return find_deep(mid+1, r);
	else return find_deep(l, mid);
}

bool dead[90010];
void muko(int z){
	queue<int> q;
	q.push(z);
	dead[z]=1;
	for(;q.size();){
		int x = q.front(); q.pop();
		for(int ei:e[x]){
			int y=es[ei]-x;
			if(dst[y]==dst[x]-1 && !dead[y]){
				dead[y]=1;
				q.push(y);
			}
		}
	}
}

void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
	// find cut vertex
	n = N;
	m = U.size();
	asking.resize(m);

	base = ask(asking);

	for(int i=0; i<m; ++i){
		int a = U[i], b = V[i];
		e[a].pb(i); e[b].pb(i);
		es[i]=a+b;
	}

	cut = find_cut(0, n-1);

	q[hd++] = cut;
	vis[cut]=1;
	while(hd>tl){
		int x=q[tl++];
		for(int ei:e[x]){
			int y=es[ei]-x;
			if(!vis[y]){
				vis[y]=1;
				dst[y]=dst[x]+1;
				q[hd++]=y;
			}
		}
	}

	int deep = find_deep(0, n-1);
	muko(deep);

	hd=tl=0;
	q[hd++] = cut;
	fill(vis, vis+n, 0);
	vis[cut]=1;
	while(hd>tl){
		int x=q[tl++];
		for(int ei:e[x]){
			int y=es[ei]-x;
			if(dead[y]) continue;
			if(!vis[y]){
				vis[y]=1;
				q[hd++]=y;
			}
		}
	}

	int d2 = find_deep(0, hd-1);
	answer(deep, d2);
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 6 / 6
• Subtask 4: 33 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31