Submission #59217

#	Time	Username	Problem	Language	Result	Execution time	Memory
59217		gusfring	Election Campaign (JOI15_election_campaign)	C++14	100 / 100	760 ms	96844 KiB

election_campaign

#include <bits/stdc++.h>
using namespace std;
const int MAX = (1e5)+1;
 
int n, m;
vector<int> g[MAX];
vector<tuple<int,int,int> > paths[MAX];
 
int d[MAX];
vector<int> anc[MAX];
void init_lca(int u, int p) {
	for(int v: g[u]) if(v != p) {
		d[v] = d[u] + 1;
		anc[v].push_back(u);
		for(int j = 0; 1 << j+1 <= d[v]; j++)
			anc[v].push_back(anc[anc[v][j]][j]);
		init_lca(v, u);
	}
}
int query_lca(int u, int v) {
	if(d[u] > d[v]) {
		int diff = d[u] - d[v];
		for(int j = anc[u].size()-1; j >= 0; j--) if(diff >> j & 1) u = anc[u][j];
	} else if(d[u] < d[v]) {
		int diff = d[v] - d[u];
		for(int j = anc[v].size()-1; j >= 0; j--) if(diff >> j & 1) v = anc[v][j];
	}
	if(u == v) return u;
	for(int j = anc[u].size()-1; j >= 0; j--) if(j < anc[u].size() && anc[u][j] != anc[v][j]) {
		u = anc[u][j];
		v = anc[v][j];
	}
	return anc[u][0];
}
 
int dp[MAX], sum[MAX], c[MAX];
map<int, int> mpf[MAX];
void dfs(int u, int p) {
	for(int v: g[u]) if(v != p) {
		dfs(v, u);
		sum[u] += dp[v];
		if(mpf[v].size() > mpf[u].size()) {
			mpf[u].swap(mpf[v]);
			swap(c[u], c[v]);
		}
		for(auto pp: mpf[v]) mpf[u][pp.first] = pp.second + c[v] - c[u];
	}
	dp[u] = sum[u];
	for(auto path: paths[u]) {
		int a, b, w;
		tie(a, b, w) = path;
		int down1 = (a != u ? mpf[u][a] + c[u] : 0);
		int down2 = (b != u ? mpf[u][b] + c[u] : 0);
		dp[u] = max(sum[u] + down1 + down2 + w, dp[u]);
	}
	mpf[u][u] = -c[u];
	c[u] += sum[u] - dp[u];
}
 
int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin >> n;
	bool ok = true, ok2 = true;
	for(int i = 1, u, v; i < n; i++) {
		cin >> u >> v; --u; --v;
		if(u != v - 1) ok = false;
		g[u].push_back(v);
		g[v].push_back(u);
	}
	init_lca(0, -1);
	cin >> m;
	for(int i = 0, u, v, w; i < m; i++) {
		cin >> u >> v >> w; --u; --v;
		if(w != 1) ok2 = false;
		paths[query_lca(u, v)].emplace_back(u, v, w);
	}
	dfs(0, -1);
	cout << dp[0];
}

Compilation message (stderr)

election_campaign.cpp: In function 'void init_lca(int, int)':
election_campaign.cpp:15:24: warning: suggest parentheses around '+' inside '<<' [-Wparentheses]
   for(int j = 0; 1 << j+1 <= d[v]; j++)
                       ~^~
election_campaign.cpp: In function 'int query_lca(int, int)':
election_campaign.cpp:29:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int j = anc[u].size()-1; j >= 0; j--) if(j < anc[u].size() && anc[u][j] != anc[v][j]) {
                                               ~~^~~~~~~~~~~~~~~
election_campaign.cpp: In function 'int main()':
election_campaign.cpp:64:7: warning: variable 'ok' set but not used [-Wunused-but-set-variable]
  bool ok = true, ok2 = true;
       ^~
election_campaign.cpp:64:18: warning: variable 'ok2' set but not used [-Wunused-but-set-variable]
  bool ok = true, ok2 = true;
                  ^~~

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