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답안 #35931

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
35931 2017-12-03T07:13:42 Z szawinis Chase (CEOI17_chase) C++14
0 / 100
 569 ms 335076 KB 
#include <bits/stdc++.h>
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;
			}
		}
	}
}

void dfs2(int u, int p) {
	for(int v: g[u]) if(v != p) dfs2(v, u);
	vector<ll> mx(lim+1);
	ans = max(s[u] + a[p], ans);
	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);
		}

		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);
		}

		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);
	printf("%lld", ans);
}

Compilation message

chase.cpp: In function 'int main()':
chase.cpp:73:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &n, &lim);
                          ^
chase.cpp:74:46: 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:76:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &u, &v);
                         ^

Subtask #1
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 Incorrect 0 ms 324288 KB Output isn't correct
6 Halted 0 ms 0 KB -

Subtask #2
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 Incorrect 0 ms 324288 KB Output isn't correct
6 Halted 0 ms 0 KB -

Subtask #3
0 / 30.0

# 결과 실행 시간 메모리 Grader output
1 Incorrect 569 ms 335076 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
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 Incorrect 0 ms 324288 KB Output isn't correct
6 Halted 0 ms 0 KB -