Submission #56841

#	Time	Username	Problem	Language	Result	Execution time	Memory
56841		Bruteforceman	Election Campaign (JOI15_election_campaign)	C++11	100 / 100	622 ms	143952 KiB

election_campaign

#include <bits/stdc++.h>
using namespace std;
vector <int> g[100010];
int anc[20][100010];
const int logn = 19;
int dep[100010];
vector <int> path[100010];
int a[100010], b[100010], c[100010];

void dfs(int x, int par) {
	anc[0][x] = par;
	for(int i = 1; i <= logn; i++) {
		anc[i][x] = anc[i - 1][anc[i - 1][x]];
	} 
	for(auto i : g[x]) {
		if(i - par) {
			dep[i] = 1 + dep[x];
			dfs(i, x);
		}
	}
}
int lca(int p, int q) {
	if(dep[p] > dep[q]) swap(p, q);
	for(int i = logn; i >= 0; i--) {
		if(dep[q] - (1 << i) >= dep[p]) {
			q = anc[i][q];
		}
	}
	if(p == q) return p;
	for(int i = logn; i >= 0; i--) {
		if(anc[i][p] != anc[i][q]) {
			p = anc[i][p];
			q = anc[i][q];
		}
	}
	return anc[0][p];
}

long long dp[100010];
long long sum[100010];
long long sib[100010];

long long l[100010], r[100010];
int tym;
int n;

void order(int x, int par) {
	l[x] = ++tym;
	for(int i : g[x]) {
		if(i - par) {
			order(i, x);
		}
	}
	r[x] = tym;
}
long long t[100010];
void update(int x, long long val) {
	for(int i = x; i <= n; i += i & (-i)) {
		t[i] += val;
	}
}
long long query(int x) {
	long long ans = 0;
	for(int i = x; i > 0; i -= i & (-i)) {
		ans += t[i];
	}
	return ans;
}
long long query(int l, int r) {
	return query(r) - query(l - 1);
}
int get(int x, int p) {
	for(int i = logn; i >= 0; i--) {
		if(dep[x] - (1 << i) >= p) {
			x = anc[i][x];
		}
	}
	return x;
}
void calc(int x, int par) {
	dp[x] = 0;
	for(auto i : g[x]) {
		if (i - par) {
			calc(i, x);
			dp[x] += dp[i];
		}
	}
	sum[x] = dp[x];
	for(auto i : g[x]) {
		if(i - par) {
			sib[i] = sum[x] - dp[i];
		}
	}
	for(auto i : path[x]) {
		int node = get(a[i], dep[x] + 1);
		long long res = c[i];
		res += query(l[a[i]]);
		if(node != x) res -= dp[node];
		node = get(b[i], dep[x] + 1);
		res += query(l[b[i]]);
		if(node != x) res -= dp[node];
		res += sum[x];
		if(a[i] != x) res += sum[a[i]];
		if(b[i] != x) res += sum[b[i]];
		dp[x] = max(dp[x], res);
	}
	for(auto i : g[x]) {
		if(i - par) {
			update(l[i], sib[i]);
			update(r[i] + 1, -sib[i]);
		}
	}
}
	
int main(int argc, char const *argv[])
{
	int m;
	scanf("%d", &n);
	for(int i = 1; i < n; i++) {
		int p, q;
		scanf("%d %d", &p, &q);
		g[p].emplace_back(q);
		g[q].emplace_back(p);
	}
	dfs(1, 0);
	order(1, 0);
	scanf("%d", &m);
	for(int i = 1; i <= m; i++) {
		scanf("%d %d %d", &a[i], &b[i], &c[i]);
		path[lca(a[i], b[i])].emplace_back(i);
	}
	calc(1, 0);
	printf("%lld\n", dp[1]);
	return 0;
}

Compilation message (stderr)

election_campaign.cpp: In function 'int main(int, const char**)':
election_campaign.cpp:118:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
  ~~~~~^~~~~~~~~~
election_campaign.cpp:121:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &p, &q);
   ~~~~~^~~~~~~~~~~~~~~~~
election_campaign.cpp:127:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &m);
  ~~~~~^~~~~~~~~~
election_campaign.cpp:129:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d %d", &a[i], &b[i], &c[i]);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 30 / 30
• Subtask 5: 10 / 10
• Subtask 6: 40 / 40