Submission #391894

#	Time	Username	Problem	Language	Result	Execution time	Memory
391894		8e7	007 (CEOI14_007)	C++14	30 / 100	260 ms	15684 KiB

007

//Challenge: Accepted
#include <iostream>
#include <algorithm>
#include <vector>
#include <utility>
#include <queue>
#define ll long long
#define maxn 200005
#define pii pair<int, int>
#define ff first
#define ss second
#define io ios_base::sync_with_stdio(0);
using namespace std;
//#include <bits/extc++.h>
//using namespace __gnu_pbds;
//template<class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_upate>;

vector<int> adj[maxn];
int dep[maxn];
bool found[maxn];

void bfs(int s) {
	queue<int> que;
	que.push(s);
	dep[s] = 0;
	while (que.size()) {
		int cur = que.front();
		que.pop();
		found[cur] = 1;
		for (int v:adj[cur]) {
			if (!found[v]) {
				found[v] = 1;
				dep[v] = dep[cur] + 1;
				que.push(v);
			}
		}
	}
}
int main() {
	io
	int n, m;
	cin >> n >> m;
	int pa, pb, st, st2;
	cin >> pa >> pb >> st >> st2;
	for (int i = 0;i < m;i++) {
		int u, v;
		cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}
	int d1 = 0, d2 = 0;
	bfs(st);
	d1 = dep[pb] - dep[pa];
	int ans = dep[pb] - dep[pa];

	for (int i = 1;i <= n;i++) found[i] = 0;
	bfs(st2);
	d2 = dep[pb] - dep[pa];
	ans = min(d1, d2);
	//ans = min(ans, dep[pb] - dep[pa]);

	if (d1 != d2) cout << (ans > 0 ? ans : -1) << "\n";
	else cout << (ans > 0 ? ans - 1 : -1) << "\n";
}
/*
6 6
1 2 3 4
1 5
5 6
6 3
6 4
1 2
3 4

3 3
3 1 1 2
1 2
2 3
3 1
 */

• Subtask 1: 9 / 30
• Subtask 2: 21 / 70