Submission #62730

#	Time	Username	Problem	Language	Result	Execution time	Memory
62730		kingpig9	Bitaro’s Party (JOI18_bitaro)	C++11	100 / 100	1988 ms	416788 KiB

bitaro

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int MAXN = 1e5 + 10;
const int SQRT = 320;

#define debug(...) fprintf(stderr, __VA_ARGS__)
#define fi first
#define se second
#define all(v) (v).begin(), (v).end()
#define fillchar(a, s) memset((a), (s), sizeof(a))

int N, M, Q;
vector<int> adj[MAXN], radj[MAXN];
vector<pii> far[MAXN];	//farthest SQRT vertices: pair(dist, vertex)

pii tmp[2 * SQRT];
bool vis[MAXN];

void merge (vector<pii> &v, const vector<pii> &w) {
	int sz = merge(all(v), all(w), tmp, greater<pii> ()) - tmp;
	v.clear();
	for (int i = 0; i < sz && v.size() < SQRT; i++) {
		if (!vis[tmp[i].se]) {
			v.push_back(tmp[i]);
			vis[tmp[i].se] = true;
		}
	}

	for (pii p : v) {
		vis[p.se] = false;
	}
}

bool busy[MAXN];
int dp[MAXN];

int main() {
	scanf("%d %d %d", &N, &M, &Q);
	for (int i = 1; i <= M; i++) {
		int x, y;
		scanf("%d %d", &x, &y);
		adj[x].push_back(y);
		radj[y].push_back(x);
	}

	for (int i = 1; i <= N; i++) {
		far[i].push_back({0, i});
		for (int j : radj[i]) {
			vector<pii> vtmp = far[j];
			for (pii &p : vtmp) {
				p.fi++;
			}
			merge(far[i], vtmp);
		}
	}

	//if size >= SQRT then brute force
	for (int qi = 1; qi <= Q; qi++) {
		int x, sz;
		scanf("%d %d", &x, &sz);
		vector<int> vbusy(sz);
		for (int &c : vbusy) {
			scanf("%d", &c);
			busy[c] = true;
		}

		int ans = -1;
		if (sz < SQRT) {
			//the farthest away -- one of them will not be
			for (pii p : far[x]) {
				if (!busy[p.se]) {
					ans = p.fi;
					break;
				}
			}
		} else {
			//brute force
			dp[x] = 0;
			for (int i = x - 1; i >= 1; i--) {
				dp[i] = -1e9;
			}
			for (int i = x; i >= 1; i--) {
				for (int j : radj[i]) {
					dp[j] = max(dp[j], dp[i] + 1);
				}

				if (!busy[i]) {
					ans = max(ans, dp[i]);
				}
			}
		}

		printf("%d\n", ans);

		for (int c : vbusy) {
			busy[c] = false;
		}
	}
}

Compilation message (stderr)

bitaro.cpp: In function 'int main()':
bitaro.cpp:43:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d %d", &N, &M, &Q);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
bitaro.cpp:46:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &x, &y);
   ~~~~~^~~~~~~~~~~~~~~~~
bitaro.cpp:65:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &x, &sz);
   ~~~~~^~~~~~~~~~~~~~~~~~
bitaro.cpp:68:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d", &c);
    ~~~~~^~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 7 / 7
• Subtask 3: 86 / 86