Submission #391830

#	Time	Username	Problem	Language	Result	Execution time	Memory
391830		Kevin_Zhang_TW	007 (CEOI14_007)	C++17	30 / 100	286 ms	17508 KiB

007

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define pb emplace_back
#define AI(i) begin(i), end(i)
template<class T> bool chmin(T &a, T b) { return b < a && (a = b, true); }
template<class T> bool chmax(T &a, T b) { return a < b && (a = b, true); }
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void kout() { cerr << endl; }
template<class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ', kout(b...); }
template<class T> void debug(T l, T r) { while (l != r) cerr << *l << " \n"[next(l)==r], ++l; }
#else
#define DE(...) 0
#define debug(...) 0
#endif

const int MAX_N = 200010, inf = 1e9;

int n, m, s, d, A, B;
vector<int> edge[MAX_N];

int diss[MAX_N], disd[MAX_N], disa[MAX_N], disb[MAX_N];

void get_dis(int s, int *dis) {
	fill(dis, dis + n + 1, inf);

	queue<int> q;
	q.emplace(s); dis[s] = 0;
	while (q.size()) {
		int x = q.front(); q.pop();
		for (int u : edge[x])
			if (chmin(dis[u], dis[x] + 1))
				q.emplace(u);
	}
}
bool valid(int rest) {
	auto test = [&](int x) {
		int art = diss[x] + rest;
		int ga = art + disa[x], gb = art + disb[x];
		if (max(disa[x], disb[x]) > 1) return false;

		int da = disd[A], db = disd[B];

		if (min(disa[x], disb[x]) == 1) {
			if (art <= min(da, db)) return true;
			return false;
		}

		if (ga <= da && gb <= db) return true;

		return false;
	};

	for (int i = 1;i <= n;++i)
		if (test(i)) return true;
	return false;

}
	
int32_t main() {
	ios_base::sync_with_stdio(0), cin.tie(0);
	cin >> n >> m >> s >> d >> A >> B;
	for (int a, b, i = 0;i < m;++i) {
		cin >> a >> b;
		DE(a, b);
		edge[a].pb(b), edge[b].pb(a);
	}
	get_dis(s, diss), get_dis(d, disd);
	get_dis(A, disa), get_dis(B, disb);

	if (!valid(0)) return puts("-1"), 0;

	int l = 0, r = n, mid;
	while (l < r) {
		mid = l + r >> 1;
		if (valid(mid+1))
			l = mid + 1;
		else
			r = mid;
	}
	cout << l << '\n';
}

Compilation message (stderr)

007.cpp: In function 'int32_t main()':
007.cpp:14:17: warning: statement has no effect [-Wunused-value]
   14 | #define DE(...) 0
      |                 ^
007.cpp:66:3: note: in expansion of macro 'DE'
   66 |   DE(a, b);
      |   ^~
007.cpp:76:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   76 |   mid = l + r >> 1;
      |         ~~^~~

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