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답안 #35935

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
35935 2017-12-03T07:55:48 Z szawinis Chase (CEOI17_chase) C++14
100 / 100
 713 ms 334364 KB 
#include <cstdio>
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
using ll = long long;
const int N = 1e5+1, V = 102;
const ll INF = 1e17;

int n, lim, a[N];
ll ans, s[N], dp[N][V][2][2]; // vertex, cnt, dir = down, up, last
vector<int> g[N];

void dfs1(int u, int p) {
	s[u] -= a[p];
	dp[u][0][0][0] = 0;
	dp[u][0][1][0] = 0;
	dp[u][1][0][1] = s[u];
	dp[u][1][1][1] = s[u];

	for(int v: g[u]) if(v != p) {
		dfs1(v, u);
		for(int x = 0; x <= lim; x++) {
			ll res[2][2] = {
				{
					max(dp[v][x][0][0], dp[v][x][0][1]),
					(x > 0 ? max(dp[v][x-1][0][0], dp[v][x-1][0][1]) + s[u] : -INF) // a[v] - a[v] cancel
				},
				{
					max(dp[v][x][1][0], dp[v][x][1][1] + a[u]),
					(x > 0 ? max(dp[v][x-1][1][0], dp[v][x-1][1][1] + a[u]) + s[u] - a[v] : -INF)
				}
			};
			for(int i = 0; i < 2; i++) for(int j = 0; j < 2; j++) {
				dp[u][x][i][j] = max(res[i][j], dp[u][x][i][j]);
				if(dp[u][x][i][j] < 0) dp[u][x][i][j] = -INF;
				// cout << u << ' ' << x << ' ' << i << ' ' << j << ' ' << dp[u][x][i][j] << endl;
			}
		}
	}
}

void dfs2(int u, int p) {
	for(int x = 0; x <= lim; x++)
		for(int i = 0; i < 2; i++)
			for(int j = 0; j < 2; j++) ans = max(dp[u][x][i][j] + bool(j) * a[p], ans);

	for(int v: g[u]) if(v != p) dfs2(v, u);
	vector<ll> mx(lim+1);
	for(int v: g[u]) if(v != p) {
		for(int x = 0; x <= lim; x++) {
			ll res = max(dp[v][x][1][0], dp[v][x][1][1] + a[u]);
			res += max((x < lim ? mx[lim-x-1] + s[u] - a[v] + a[p] : 0), mx[lim-x]);
			ans = max(res, ans);
			// cout << u << ' ' << v << ' ' << x << ' ' << res << endl;
		}

		for(int x = 0; x <= lim; x++) {
			mx[x] = max(max(dp[v][x][0][0], dp[v][x][0][1]), mx[x]);
			mx[x] = max((x > 0 ? mx[x-1] : 0), mx[x]);
		}
	}
	reverse(g[u].begin(), g[u].end());
	mx.clear();
	mx.resize(lim+1);
	for(int v: g[u]) if(v != p) {
		for(int x = 0; x <= lim; x++) {
			ll res = max(dp[v][x][1][0], dp[v][x][1][1] + a[u]);
			res += max((x < lim ? mx[lim-x-1] + s[u] - a[v] + a[p] : 0), mx[lim-x]);
			ans = max(res, ans);
			// cout << u << ' ' << v << ' ' << x << ' ' << res << endl;
		}

		for(int x = 0; x <= lim; x++) {
			mx[x] = max(max(dp[v][x][0][0], dp[v][x][0][1]), mx[x]);
			mx[x] = max((x > 0 ? mx[x-1] : 0), mx[x]);
		}
	}
}

int main() {
	scanf("%d %d", &n, &lim);
	for(int i = 1; i <= n; i++) scanf("%d", a+i);
	for(int i = 1, u, v; i < n; i++) {
		scanf("%d %d", &u, &v);
		g[u].push_back(v);
		g[v].push_back(u);
		s[u] += a[v];
		s[v] += a[u];
	}
	for(int v = 0; v <= n; v++)
		for(int x = 0; x <= lim; x++)
			for(int i = 0; i < 2; i++) for(int j = 0; j < 2; j++) dp[v][x][i][j] = -INF;

	dfs1(1, 0);
	dfs2(1, 0);
	// for(int x = 0; x <= lim; x++) for(int i = 0; i < 2; i++) for(int j = 0; j < 2; j++) ans = max(dp[1][x][i][j], ans);
	printf("%lld", ans);
}

Compilation message

chase.cpp: In function 'int main()':
chase.cpp:82:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &n, &lim);
                          ^
chase.cpp:83:46: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(int i = 1; i <= n; i++) scanf("%d", a+i);
                                              ^
chase.cpp:85:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &u, &v);
                         ^

Subtask #1
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 324288 KB Output is correct
2 Correct 0 ms 324288 KB Output is correct
3 Correct 0 ms 324288 KB Output is correct
4 Correct 0 ms 324288 KB Output is correct
5 Correct 0 ms 324288 KB Output is correct
6 Correct 0 ms 324288 KB Output is correct

Subtask #2
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 324288 KB Output is correct
2 Correct 0 ms 324288 KB Output is correct
3 Correct 0 ms 324288 KB Output is correct
4 Correct 0 ms 324288 KB Output is correct
5 Correct 0 ms 324288 KB Output is correct
6 Correct 0 ms 324288 KB Output is correct
7 Correct 6 ms 324288 KB Output is correct
8 Correct 3 ms 324288 KB Output is correct
9 Correct 0 ms 324288 KB Output is correct
10 Correct 3 ms 324288 KB Output is correct
11 Correct 6 ms 324288 KB Output is correct
12 Correct 0 ms 324288 KB Output is correct

Subtask #3
30.0 / 30.0

# 결과 실행 시간 메모리 Grader output
1 Correct 669 ms 334308 KB Output is correct
2 Correct 649 ms 334268 KB Output is correct
3 Correct 456 ms 328004 KB Output is correct
4 Correct 179 ms 327588 KB Output is correct
5 Correct 683 ms 327588 KB Output is correct
6 Correct 676 ms 327588 KB Output is correct
7 Correct 686 ms 327588 KB Output is correct

Subtask #4
30.0 / 30.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 324288 KB Output is correct
2 Correct 0 ms 324288 KB Output is correct
3 Correct 0 ms 324288 KB Output is correct
4 Correct 0 ms 324288 KB Output is correct
5 Correct 0 ms 324288 KB Output is correct
6 Correct 0 ms 324288 KB Output is correct
7 Correct 6 ms 324288 KB Output is correct
8 Correct 3 ms 324288 KB Output is correct
9 Correct 0 ms 324288 KB Output is correct
10 Correct 3 ms 324288 KB Output is correct
11 Correct 6 ms 324288 KB Output is correct
12 Correct 0 ms 324288 KB Output is correct
13 Correct 669 ms 334308 KB Output is correct
14 Correct 649 ms 334268 KB Output is correct
15 Correct 456 ms 328004 KB Output is correct
16 Correct 179 ms 327588 KB Output is correct
17 Correct 683 ms 327588 KB Output is correct
18 Correct 676 ms 327588 KB Output is correct
19 Correct 686 ms 327588 KB Output is correct
20 Correct 663 ms 327588 KB Output is correct
21 Correct 149 ms 327588 KB Output is correct
22 Correct 699 ms 327588 KB Output is correct
23 Correct 183 ms 327588 KB Output is correct
24 Correct 713 ms 327588 KB Output is correct
25 Correct 503 ms 328004 KB Output is correct
26 Correct 686 ms 334364 KB Output is correct
27 Correct 659 ms 334364 KB Output is correct