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답안 #392022

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
392022 2021-04-20T10:02:34 Z AriaH Chase (CEOI17_chase) C++11
100 / 100
 1504 ms 251440 KB 
/** I can do this all day **/

#pragma GCC optimize("O2")
#include <bits/stdc++.h>
using namespace std;

typedef long long                   ll;
typedef long double                 ld;
typedef pair<int,int>               pii;
typedef pair<ll,ll>                 pll;
#define all(x)                      (x).begin(),(x).end()
#define F                           first
#define S                           second
#define Mp                          make_pair
#define SZ(x)			    		(int)x.size()
#define fast_io                     ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io                     freopen("in.txt" , "r+" , stdin) ; freopen("out.txt" , "w+" , stdout);

const int N = 1e5 + 5;
const ll mod = 1e9 + 7;
const ll mod2 = 998244353;
const ll inf = 1e18;
const int LOG = 22;
const int M = 1e2 + 5;

int n, k, Par[N];

vector < int > G[N];

ll tot, A[N], nei[N], dp_down[2][M][N], dp_up[M][N];

void dfs_down(int v, int P)
{
	Par[v] = P;
	dp_up[1][v] = nei[v];
	for(auto u : G[v])
	{
		if(u == P) continue;
		dfs_down(u, v);
		for(int x = 0; x <= k; x ++)
		{
			dp_up[x][v] = max(dp_up[x][v], dp_up[x][u]);
			if(x) 
			{
				dp_up[x][v] = max(dp_up[x][v], dp_up[x - 1][u] + nei[v] - A[u]);
			}
		}
	}
}

void dfs(int v, int P)
{
	for(int i = 1; i <= k; i ++)
	{
		dp_down[1][i][v] = nei[v] - A[P];
	}
	dp_down[1][0][v] = -inf;
	for(auto u : G[v])
	{
		if(u == P) continue;
		dfs(u, v);
		for(int x = 0; x <= k; x ++)
		{
			tot = max(tot, dp_up[x][u] + dp_down[0][k - x][v]);
			if(x != k) tot = max(tot, dp_up[x][u] + dp_down[1][k - x][v] + A[P] - A[u]);
			///printf("x = %d v = %d u = %d cu0 = %lld cu1 = %lld\n", x, v, u, dp_up[x][u] + dp_down[0][k - x][v], dp_up[x][u] + dp_down[1][k - x][v] + A[P] - A[u]);
		}
		for(int x = 0; x <= k; x ++)
		{
			dp_down[0][x][v] = max(dp_down[0][x][v], max(dp_down[0][x][u], dp_down[1][x][u]));

			if(x)
			{
				dp_down[1][x][v] = max(dp_down[1][x][v], nei[v] - A[P] + max(dp_down[1][x - 1][u], dp_down[0][x - 1][u]));
			}
		}
	}
	reverse(all(G[v]));
	for(int i = 0; i < M; i ++) dp_down[0][i][v] = dp_down[1][i][v] = 0;
	for(int i = 1; i <= k; i ++) dp_down[1][i][v] = nei[v] - A[P];
	dp_down[1][0][v] = -inf;
	for(auto u : G[v])
	{
		if(u == P) continue;
		///dfs(u, v);
		for(int x = 0; x <= k; x ++)
		{
			tot = max(tot, dp_up[x][u] + dp_down[0][k - x][v]);
			if(x != k) tot = max(tot, dp_up[x][u] + dp_down[1][k - x][v] + A[P] - A[u]);
		}
		for(int x = 0; x <= k; x ++)
		{
			dp_down[0][x][v] = max(dp_down[0][x][v], max(dp_down[0][x][u], dp_down[1][x][u]));

			if(x)
			{
				dp_down[1][x][v] = max(dp_down[1][x][v], nei[v] - A[P] + max(dp_down[1][x - 1][u], dp_down[0][x - 1][u]));
			}
		}
	}
}

int main()
{
	scanf("%d%d", &n, &k);
    for(int i = 1; i <= n; i ++)
	{
		scanf("%lld", &A[i]);
	}
	for(int i = 1; i < n; i ++)
	{
		int a, b;
		scanf("%d%d", &a, &b);
		G[a].push_back(b);
		G[b].push_back(a);
		nei[a] += A[b];
		nei[b] += A[a];
	}
	dfs_down(1, 0);
	dfs(1, 0);
	for(int i = 1; i <= n; i ++)
	{
		tot = max(tot, dp_down[1][k][i] + A[Par[i]]);
		tot = max(tot, dp_up[k][i]);
	}
	/*for(int i = 1; i <= n; i ++)
	{
	    for(int j = 1; j <= k; j ++)
	    {
		printf("i = %d j = %d dp = %lld\n", i, j, dp_up[j][i]);
	    }
	}
	*/
	printf("%lld", tot);
	return 0;
}

/** test corner cases(n = 1?) watch for overflow or minus indices **/

Compilation message

chase.cpp: In function 'int main()':
chase.cpp:105:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  105 |  scanf("%d%d", &n, &k);
      |  ~~~~~^~~~~~~~~~~~~~~~
chase.cpp:108:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  108 |   scanf("%lld", &A[i]);
      |   ~~~~~^~~~~~~~~~~~~~~
chase.cpp:113:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  113 |   scanf("%d%d", &a, &b);
      |   ~~~~~^~~~~~~~~~~~~~~~

Subtask #1
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 3788 KB Output is correct
2 Correct 2 ms 3788 KB Output is correct
3 Correct 2 ms 3788 KB Output is correct
4 Correct 2 ms 3788 KB Output is correct
5 Correct 3 ms 3788 KB Output is correct
6 Correct 2 ms 3788 KB Output is correct

Subtask #2
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 3788 KB Output is correct
2 Correct 2 ms 3788 KB Output is correct
3 Correct 2 ms 3788 KB Output is correct
4 Correct 2 ms 3788 KB Output is correct
5 Correct 3 ms 3788 KB Output is correct
6 Correct 2 ms 3788 KB Output is correct
7 Correct 7 ms 6476 KB Output is correct
8 Correct 4 ms 5524 KB Output is correct
9 Correct 4 ms 5452 KB Output is correct
10 Correct 7 ms 6732 KB Output is correct
11 Correct 5 ms 5836 KB Output is correct
12 Correct 4 ms 5580 KB Output is correct

Subtask #3
30.0 / 30.0

# 결과 실행 시간 메모리 Grader output
1 Correct 856 ms 217992 KB Output is correct
2 Correct 873 ms 217928 KB Output is correct
3 Correct 463 ms 174252 KB Output is correct
4 Correct 541 ms 173856 KB Output is correct
5 Correct 1499 ms 250508 KB Output is correct
6 Correct 1504 ms 251440 KB Output is correct
7 Correct 1497 ms 251172 KB Output is correct

Subtask #4
30.0 / 30.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 3788 KB Output is correct
2 Correct 2 ms 3788 KB Output is correct
3 Correct 2 ms 3788 KB Output is correct
4 Correct 2 ms 3788 KB Output is correct
5 Correct 3 ms 3788 KB Output is correct
6 Correct 2 ms 3788 KB Output is correct
7 Correct 7 ms 6476 KB Output is correct
8 Correct 4 ms 5524 KB Output is correct
9 Correct 4 ms 5452 KB Output is correct
10 Correct 7 ms 6732 KB Output is correct
11 Correct 5 ms 5836 KB Output is correct
12 Correct 4 ms 5580 KB Output is correct
13 Correct 856 ms 217992 KB Output is correct
14 Correct 873 ms 217928 KB Output is correct
15 Correct 463 ms 174252 KB Output is correct
16 Correct 541 ms 173856 KB Output is correct
17 Correct 1499 ms 250508 KB Output is correct
18 Correct 1504 ms 251440 KB Output is correct
19 Correct 1497 ms 251172 KB Output is correct
20 Correct 1490 ms 251416 KB Output is correct
21 Correct 512 ms 173892 KB Output is correct
22 Correct 1489 ms 251384 KB Output is correct
23 Correct 531 ms 173764 KB Output is correct
24 Correct 1481 ms 251360 KB Output is correct
25 Correct 433 ms 173756 KB Output is correct
26 Correct 859 ms 217960 KB Output is correct
27 Correct 858 ms 218140 KB Output is correct