Submission #129637

# Submission time Handle Problem Language Result Execution time Memory
129637 2019-07-12T20:34:06 Z luciocf Cat in a tree (BOI17_catinatree) C++14
100 / 100
495 ms 38636 KB
#include <bits/stdc++.h>

using namespace std;

const int maxn = 2e5+10;
const int inf = 1e9+10;

int n, D;

int order[maxn];

int sz[maxn], nivel[maxn];

int pai[maxn], dist[maxn][20];
int sub[maxn];

bool mark[maxn];

vector<int> grafo[maxn];

void dfsPre(int u, int p)
{
	for (auto v: grafo[u])
	{
		if (v == p) continue;

		nivel[v] = nivel[u]+1;
		dfsPre(v, u);
	}
}

void dfs(int u, int p)
{
	sz[u] = 1;
	for (auto v: grafo[u])
	{
		if (v == p || mark[v]) continue;

		dfs(v, u);
		sz[u] += sz[v];
	}
}

int centroid(int u, int p, int S)
{
	for (auto v: grafo[u])
		if (v != p && !mark[v] && sz[v] > S/2)
			return centroid(v, u, S);

	return u;
}

void upd(int u, int p, int x, int lvl)
{
	dist[u][lvl] = x;

	for (auto v: grafo[u])
		if (v != p && !mark[v])
			upd(v, u, x+1, lvl);
}

void decompose(int u, int p, int lvl)
{
	dfs(u, 0);

	int c = centroid(u, 0, sz[u]);

	mark[c] = true;
	pai[c] = p, nivel[c] = lvl;

	upd(c, 0, 0, lvl);

	for (auto v: grafo[c])
		if (!mark[v])
			decompose(v, c, lvl+1);
}

bool comp(int a, int b)
{
	return nivel[a] > nivel[b];
}

int main(void)
{
	scanf("%d %d", &n, &D);

	for (int i = 2; i <= n; i++)
	{
		int v;
		scanf("%d", &v);
		++v;

		grafo[i].push_back(v); grafo[v].push_back(i);
	}

	for (int i = 1; i <= n; i++)
	{
		order[i] = i;
		sub[i] = inf;
	}

	dfsPre(1, 0);
	sort(order+1, order+n+1, comp);

	decompose(1, 0, 0);

	int ans = 0;

	for (int i = 1; i <= n; i++)
	{
		int u = order[i], v = u;
		int mn = inf;

		while (v)
		{
			mn = min(mn, dist[u][nivel[v]] + sub[v]);
			v = pai[v];
		}

		if (mn < D) continue;

		++ans, v = u;

		while (v)
		{
			sub[v] = min(sub[v], dist[u][nivel[v]]);
			v = pai[v];
		}
	}

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

/*
	* bounds (maxn)
	* long long
	* all variables reset?
	* check if indexing is ok
	* off by one? (n-i+1) or (n-i)?
	* edge cases (n=0, n=1, n < 0, n=maxn)
*/

Compilation message

catinatree.cpp: In function 'int main()':
catinatree.cpp:85:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &n, &D);
  ~~~~~^~~~~~~~~~~~~~~~~
catinatree.cpp:90:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &v);
   ~~~~~^~~~~~~~~~
# Verdict Execution time Memory Grader output
1 Correct 7 ms 5112 KB Output is correct
2 Correct 6 ms 5112 KB Output is correct
3 Correct 6 ms 5112 KB Output is correct
4 Correct 6 ms 5112 KB Output is correct
5 Correct 7 ms 5112 KB Output is correct
6 Correct 6 ms 5112 KB Output is correct
7 Correct 6 ms 5032 KB Output is correct
8 Correct 6 ms 5112 KB Output is correct
9 Correct 6 ms 5112 KB Output is correct
10 Correct 8 ms 4984 KB Output is correct
11 Correct 7 ms 5112 KB Output is correct
12 Correct 7 ms 4988 KB Output is correct
13 Correct 6 ms 5112 KB Output is correct
14 Correct 6 ms 4984 KB Output is correct
15 Correct 6 ms 5112 KB Output is correct
16 Correct 7 ms 5112 KB Output is correct
17 Correct 6 ms 5112 KB Output is correct
18 Correct 6 ms 5112 KB Output is correct
19 Correct 6 ms 5112 KB Output is correct
20 Correct 6 ms 4984 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 7 ms 5112 KB Output is correct
2 Correct 6 ms 5112 KB Output is correct
3 Correct 6 ms 5112 KB Output is correct
4 Correct 6 ms 5112 KB Output is correct
5 Correct 7 ms 5112 KB Output is correct
6 Correct 6 ms 5112 KB Output is correct
7 Correct 6 ms 5032 KB Output is correct
8 Correct 6 ms 5112 KB Output is correct
9 Correct 6 ms 5112 KB Output is correct
10 Correct 8 ms 4984 KB Output is correct
11 Correct 7 ms 5112 KB Output is correct
12 Correct 7 ms 4988 KB Output is correct
13 Correct 6 ms 5112 KB Output is correct
14 Correct 6 ms 4984 KB Output is correct
15 Correct 6 ms 5112 KB Output is correct
16 Correct 7 ms 5112 KB Output is correct
17 Correct 6 ms 5112 KB Output is correct
18 Correct 6 ms 5112 KB Output is correct
19 Correct 6 ms 5112 KB Output is correct
20 Correct 6 ms 4984 KB Output is correct
21 Correct 7 ms 5468 KB Output is correct
22 Correct 6 ms 5112 KB Output is correct
23 Correct 6 ms 5112 KB Output is correct
24 Correct 6 ms 5112 KB Output is correct
25 Correct 7 ms 5112 KB Output is correct
26 Correct 7 ms 5112 KB Output is correct
27 Correct 9 ms 5240 KB Output is correct
28 Correct 7 ms 5240 KB Output is correct
29 Correct 7 ms 5240 KB Output is correct
30 Correct 7 ms 5368 KB Output is correct
31 Correct 10 ms 5240 KB Output is correct
32 Correct 7 ms 5240 KB Output is correct
33 Correct 8 ms 5240 KB Output is correct
34 Correct 8 ms 5240 KB Output is correct
35 Correct 8 ms 5240 KB Output is correct
36 Correct 7 ms 5240 KB Output is correct
37 Correct 7 ms 5240 KB Output is correct
38 Correct 8 ms 5240 KB Output is correct
39 Correct 7 ms 5240 KB Output is correct
40 Correct 7 ms 5368 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 7 ms 5112 KB Output is correct
2 Correct 6 ms 5112 KB Output is correct
3 Correct 6 ms 5112 KB Output is correct
4 Correct 6 ms 5112 KB Output is correct
5 Correct 7 ms 5112 KB Output is correct
6 Correct 6 ms 5112 KB Output is correct
7 Correct 6 ms 5032 KB Output is correct
8 Correct 6 ms 5112 KB Output is correct
9 Correct 6 ms 5112 KB Output is correct
10 Correct 8 ms 4984 KB Output is correct
11 Correct 7 ms 5112 KB Output is correct
12 Correct 7 ms 4988 KB Output is correct
13 Correct 6 ms 5112 KB Output is correct
14 Correct 6 ms 4984 KB Output is correct
15 Correct 6 ms 5112 KB Output is correct
16 Correct 7 ms 5112 KB Output is correct
17 Correct 6 ms 5112 KB Output is correct
18 Correct 6 ms 5112 KB Output is correct
19 Correct 6 ms 5112 KB Output is correct
20 Correct 6 ms 4984 KB Output is correct
21 Correct 7 ms 5468 KB Output is correct
22 Correct 6 ms 5112 KB Output is correct
23 Correct 6 ms 5112 KB Output is correct
24 Correct 6 ms 5112 KB Output is correct
25 Correct 7 ms 5112 KB Output is correct
26 Correct 7 ms 5112 KB Output is correct
27 Correct 9 ms 5240 KB Output is correct
28 Correct 7 ms 5240 KB Output is correct
29 Correct 7 ms 5240 KB Output is correct
30 Correct 7 ms 5368 KB Output is correct
31 Correct 10 ms 5240 KB Output is correct
32 Correct 7 ms 5240 KB Output is correct
33 Correct 8 ms 5240 KB Output is correct
34 Correct 8 ms 5240 KB Output is correct
35 Correct 8 ms 5240 KB Output is correct
36 Correct 7 ms 5240 KB Output is correct
37 Correct 7 ms 5240 KB Output is correct
38 Correct 8 ms 5240 KB Output is correct
39 Correct 7 ms 5240 KB Output is correct
40 Correct 7 ms 5368 KB Output is correct
41 Correct 211 ms 30996 KB Output is correct
42 Correct 175 ms 18808 KB Output is correct
43 Correct 164 ms 18684 KB Output is correct
44 Correct 165 ms 18680 KB Output is correct
45 Correct 151 ms 18844 KB Output is correct
46 Correct 388 ms 32632 KB Output is correct
47 Correct 424 ms 32576 KB Output is correct
48 Correct 495 ms 32396 KB Output is correct
49 Correct 430 ms 32348 KB Output is correct
50 Correct 101 ms 19068 KB Output is correct
51 Correct 118 ms 19064 KB Output is correct
52 Correct 106 ms 19064 KB Output is correct
53 Correct 275 ms 32860 KB Output is correct
54 Correct 286 ms 32892 KB Output is correct
55 Correct 399 ms 32828 KB Output is correct
56 Correct 9 ms 5368 KB Output is correct
57 Correct 26 ms 9208 KB Output is correct
58 Correct 122 ms 24312 KB Output is correct
59 Correct 407 ms 38636 KB Output is correct
60 Correct 222 ms 31604 KB Output is correct
61 Correct 234 ms 31096 KB Output is correct