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Submission #115924

# Submission time Handle Problem Language Result Execution time Memory
115924 2019-06-09T23:18:27 Z luciocf Tug of War (BOI15_tug) C++14
23 / 100
 17 ms 3200 KB 
#include <bits/stdc++.h>

#define ff first
#define ss second

using namespace std;

const int maxn = 6e4+10;

typedef pair<int, int> pii;

int n, k;

int sa, sb;

int pai[maxn], edge[maxn];

int firstCycle[maxn], lastCycle[maxn], inCycle[maxn];
int comp[maxn], back[maxn];

int freq[20*maxn];
bool dp[20*maxn];

bool mark[maxn];

vector<int> V;

vector<pii> grafo[maxn];

int msb(int x)
{
	return 31-__builtin_clz(x);
}

void dfs(int u, int p, int cc)
{
	comp[u] = cc;

	for (auto pp: grafo[u])
	{
		int v = pp.ff, w = pp.ss;

		if (comp[v])
		{
			if (v != p)
			{
				firstCycle[cc] = u, lastCycle[cc] = v;
				back[cc] = w;
			}
			continue;
		}

		pai[v] = u, edge[v] = w;

		dfs(v, u, cc);
	}
}

void markCycle(int cc)
{
	int u = firstCycle[cc], v = lastCycle[cc];

	int s0 = 0, s1 = back[cc];
	bool turn = 0;

	while (true)
	{
		inCycle[v] = true;

		if (!turn) s0 += edge[v];
		else s1 += edge[v];

		if (u == v) break;

		v = pai[v];
		turn = !turn;
	}

	if (s0 > s1)
		++freq[s0], ++freq[s0-s1];
	else
		++freq[s1], ++freq[s1-s0];
}

void dfs2(int u)
{
	mark[u] = true;

	for (auto pp: grafo[u])
	{
		int v = pp.ff;
		if (!mark[v])
			dfs2(v);
	}

	if (!inCycle[u])
	{
		if (u <= n) sa += edge[u];
		else sb += edge[u];
	}
}

int main(void)
{
	memset(firstCycle, -1, sizeof firstCycle);

	scanf("%d %d", &n, &k);

	int S = 0;

	for (int i = 1; i <= 2*n; i++)
	{
		int a, b, w;
		scanf("%d %d %d", &a, &b, &w);

		b += n;
		S += w;

		grafo[a].push_back({b, w});
		grafo[b].push_back({a, w});
	}

	int cc = 0;
	for (int i = 1; i <= 2*n; i++)
	{
		if (comp[i]) continue;

		dfs(i, 0, ++cc);

		if (firstCycle[cc] == -1)
		{
			printf("NO\n");
			return 0;
		}
	}

	for (int i = 1; i <= cc; i++)
	{
		markCycle(i);
		dfs2(firstCycle[i]);
	}

	for (int i = 0; i <= S; i++)
	{
		if (freq[i] == 0) continue;

		int x = msb(freq[i]);

		for (int j = 0; j < x; j++)
			V.push_back((1<<j)*i);

		V.push_back(i*(freq[i]-(1<<x)+1));
	}

	// solve a
	dp[0] = 1;
	for (auto w: V)
		for (int i = (S-2*sa)/2; i >= w; i--)
			dp[i] |= dp[i-w];

	int mx = 0;
	for (int i = 0; i <= (S-2*sa)/2; i++)
		if (dp[i])
			mx = max(mx, i);

	if (S-sb-2*sa-2*mx <= k)
	{
		printf("YES\n");
		return 0;
	}

	memset(dp, 0, sizeof dp);

	// solve b
	dp[0] = 1;
	for (auto w: V)
		for (int i = (S-2*sb)/2; i >= w; i--)
			dp[i] |= dp[i-w];

	mx = 0;
	for (int i = 0; i <= (S-2*sb)/2; i++)
		if (dp[i])
			mx = max(mx, i);

	if (S-sa-2*sb-2*mx <= k)
	{
		printf("YES\n");
		return 0;
	}

	printf("NO\n");
}

Compilation message

tug.cpp: In function 'int main()':
tug.cpp:107:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &n, &k);
  ~~~~~^~~~~~~~~~~~~~~~~
tug.cpp:114:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d %d", &a, &b, &w);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 3200 KB Output is correct
2 Correct 3 ms 2048 KB Output is correct
3 Correct 4 ms 3072 KB Output is correct
4 Correct 4 ms 2048 KB Output is correct
5 Correct 5 ms 3200 KB Output is correct
6 Correct 4 ms 3200 KB Output is correct
7 Correct 3 ms 2048 KB Output is correct
8 Correct 3 ms 2048 KB Output is correct
9 Correct 4 ms 2048 KB Output is correct
10 Correct 5 ms 3200 KB Output is correct
11 Correct 3 ms 2048 KB Output is correct
12 Correct 4 ms 2048 KB Output is correct
13 Correct 3 ms 2048 KB Output is correct
14 Correct 3 ms 2048 KB Output is correct
15 Correct 3 ms 2048 KB Output is correct
16 Correct 4 ms 3200 KB Output is correct
17 Correct 3 ms 2048 KB Output is correct
18 Correct 3 ms 2048 KB Output is correct
19 Correct 3 ms 2048 KB Output is correct
20 Correct 3 ms 2048 KB Output is correct
21 Correct 4 ms 2048 KB Output is correct
22 Correct 3 ms 2124 KB Output is correct
23 Incorrect 3 ms 2048 KB Output isn't correct
24 Halted 0 ms 0 KB -

Subtask #2
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 3200 KB Output is correct
2 Correct 3 ms 2048 KB Output is correct
3 Correct 4 ms 3072 KB Output is correct
4 Correct 4 ms 2048 KB Output is correct
5 Correct 5 ms 3200 KB Output is correct
6 Correct 4 ms 3200 KB Output is correct
7 Correct 3 ms 2048 KB Output is correct
8 Correct 3 ms 2048 KB Output is correct
9 Correct 4 ms 2048 KB Output is correct
10 Correct 5 ms 3200 KB Output is correct
11 Correct 3 ms 2048 KB Output is correct
12 Correct 4 ms 2048 KB Output is correct
13 Correct 3 ms 2048 KB Output is correct
14 Correct 3 ms 2048 KB Output is correct
15 Correct 3 ms 2048 KB Output is correct
16 Correct 4 ms 3200 KB Output is correct
17 Correct 3 ms 2048 KB Output is correct
18 Correct 3 ms 2048 KB Output is correct
19 Correct 3 ms 2048 KB Output is correct
20 Correct 3 ms 2048 KB Output is correct
21 Correct 4 ms 2048 KB Output is correct
22 Correct 3 ms 2124 KB Output is correct
23 Incorrect 3 ms 2048 KB Output isn't correct
24 Halted 0 ms 0 KB -

Subtask #3
23.0 / 23.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 2944 KB Output is correct
2 Correct 12 ms 2944 KB Output is correct
3 Correct 13 ms 2944 KB Output is correct
4 Correct 12 ms 2688 KB Output is correct
5 Correct 13 ms 2944 KB Output is correct
6 Correct 13 ms 2816 KB Output is correct
7 Correct 13 ms 2916 KB Output is correct
8 Correct 12 ms 2944 KB Output is correct
9 Correct 13 ms 2944 KB Output is correct
10 Correct 13 ms 2816 KB Output is correct
11 Correct 13 ms 2944 KB Output is correct
12 Correct 12 ms 2944 KB Output is correct
13 Correct 13 ms 2944 KB Output is correct
14 Correct 12 ms 2944 KB Output is correct
15 Correct 17 ms 2816 KB Output is correct
16 Correct 13 ms 2944 KB Output is correct
17 Correct 12 ms 2944 KB Output is correct
18 Correct 12 ms 2944 KB Output is correct
19 Correct 13 ms 2916 KB Output is correct
20 Correct 13 ms 2944 KB Output is correct
21 Correct 13 ms 3072 KB Output is correct
22 Correct 14 ms 3200 KB Output is correct

Subtask #4
0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 3200 KB Output is correct
2 Correct 3 ms 2048 KB Output is correct
3 Correct 4 ms 3072 KB Output is correct
4 Correct 4 ms 2048 KB Output is correct
5 Correct 5 ms 3200 KB Output is correct
6 Correct 4 ms 3200 KB Output is correct
7 Correct 3 ms 2048 KB Output is correct
8 Correct 3 ms 2048 KB Output is correct
9 Correct 4 ms 2048 KB Output is correct
10 Correct 5 ms 3200 KB Output is correct
11 Correct 3 ms 2048 KB Output is correct
12 Correct 4 ms 2048 KB Output is correct
13 Correct 3 ms 2048 KB Output is correct
14 Correct 3 ms 2048 KB Output is correct
15 Correct 3 ms 2048 KB Output is correct
16 Correct 4 ms 3200 KB Output is correct
17 Correct 3 ms 2048 KB Output is correct
18 Correct 3 ms 2048 KB Output is correct
19 Correct 3 ms 2048 KB Output is correct
20 Correct 3 ms 2048 KB Output is correct
21 Correct 4 ms 2048 KB Output is correct
22 Correct 3 ms 2124 KB Output is correct
23 Incorrect 3 ms 2048 KB Output isn't correct
24 Halted 0 ms 0 KB -