Submission #1138365

#	Time	Username	Problem	Language	Result	Execution time	Memory
1138365		SmuggingSpun	Election Campaign (JOI15_election_campaign)	C++20	100 / 100	296 ms	26696 KiB

election_campaign

#include<bits/stdc++.h>
#define taskname "A"
using namespace std;
template<class T>void maximize(T& a, T b){
	if(a < b){
		a = b;
	}
}
const int lim = 1e5 + 5;
const int INF = 1e9;
vector<int>g[lim];
int n, m, time_dfs = 0, low[lim], tail[lim], h[lim], up[lim][17];
void dfs_0(int s){
	low[s] = ++time_dfs;
	for(int& d : g[s]){
		if(d != up[s][0]){
			h[d] = h[up[d][0] = s] + 1;
			for(int i = 1; i < 17; i++){
				up[d][i] = up[up[d][i - 1]][i - 1];
			}
			dfs_0(d);
		}
	}
	tail[s] = time_dfs;
}
namespace sub1{
	bitset<lim>current, state[15];
	int c[15];
	void solve(){
		for(int i = 0; i < m; i++){
			int u, v;
			cin >> u >> v >> c[i];
			state[i].reset();
			state[i].set(u);
			state[i].set(v);
			while(u != v){
				if(h[u] < h[v]){
					swap(u, v);
				}
				state[i].set(u = up[u][0]);
			}
		}
		int ans = 0;
		for(int mask = (1 << m) - 1; mask > 0; mask--){
			current.reset();
			int sum = 0;
			bool can = true;
			for(int i = 0; i < m; i++){
				if(1 << i & mask){
					if((current & state[i]).any()){
						can = false;
						break;
					}
					current |= state[i];
					sum += c[i];
				}
			}
			if(can){
				maximize(ans, sum);
			}
		}
		cout << ans;
	}
}
namespace sub23{
	vector<pair<int, int>>segment[lim];
	int dp[lim];
	void solve(){
		for(int i = 0; i < m; i++){
			int a, b, c;
			cin >> a >> b >> c;
			if(a > b){
				swap(a, b);
			}
			segment[b].emplace_back(a, c);
		}
		dp[0] = 0;
		for(int i = 1; i <= n; i++){
			dp[i] = dp[i - 1];
			for(auto& [j, c] : segment[i]){
				maximize(dp[i], dp[j - 1] + c);
			}
		}
		cout << dp[n];
	}
}
namespace sub456{
	int bit[lim], dp[lim][2];
	void update(int p, int x){
		for(; p <= n; p += p & -p){
			bit[p] += x;
		}
	}
	void update(int l, int r, int x){
		update(l, x);
		update(r + 1, -x);
	}
	int get(int p){
		int ans = 0;
		for(; p > 0; p -= p & -p){
			ans += bit[p];
		}
		return ans;
	}
	int ancestor(int u, int k){
		for(int i = 0; i < 17; i++){
			if(1 << i & k){
				u = up[u][i];
			}
		}
		return u;
	}
	int lca(int u, int v){
		if(h[u] < h[v]){
			swap(u, v);
		}
		if((u = ancestor(u, h[u] - h[v])) == v){
			return u;
		}
		for(int i = 16; i > -1; i--){
			if(up[u][i] != up[v][i]){
				u = up[u][i];
				v = up[v][i];
			}
		}
		return up[u][0];
	}
	vector<tuple<int, int, int>>path[lim];
	void dfs_1(int s){
		dp[s][0] = 0;
		dp[s][1] = -INF;
		for(int& d : g[s]){
			if(d != up[s][0]){
				dfs_1(d);
				dp[s][0] += max(dp[d][0], dp[d][1]);
			}
		}
		for(auto& [a, b, c] : path[s]){
			maximize(dp[s][1], (a == s ? 0 : get(low[a])) + get(low[b]) + c);
		}
		update(low[s], tail[s], dp[s][0] - max(dp[s][0], dp[s][1] += dp[s][0]));
	}
	void solve(){
		for(int i = 0; i < m; i++){
			int a, b, c;
			cin >> a >> b >> c;
			if(h[a] > h[b]){
				swap(a, b);
			}
			path[lca(a, b)].emplace_back(a, b, c);
		}
		memset(bit, 0, sizeof(bit));
		dfs_1(1);
		cout << max(dp[1][0], dp[1][1]);
	}
}
int main(){
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	if(fopen(taskname".inp", "r")){
		freopen(taskname".inp", "r", stdin);
	}
	cin >> n;
	for(int i = 1; i < n; i++){
		int u, v;
		cin >> u >> v;
		g[u].emplace_back(v);
		g[v].emplace_back(u);
	}
	memset(up, 0, sizeof(up));
	dfs_0(h[1] = 1);
	cin >> m;
	if(m <= 15){
		sub1::solve();
	}
	else{
		bool is_sub23 = (g[1].size() == 1 && g[1][0] == 2);
		for(int i = 2; i < n; i++){
			if(g[i].size() != 2 || min(g[i][0], g[i][1]) != i - 1 || (g[i][0] ^ g[i][1] ^ (i - 1)) != i + 1){
				is_sub23 = false;
				break;
			}
		}
		if(is_sub23 && g[n].size() == 1 && g[n][0] == n - 1){
			sub23::solve();
		}
		else{
			sub456::solve();
		}
	}
}

Compilation message (stderr)

election_campaign.cpp: In function 'int main()':
election_campaign.cpp:160:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  160 |                 freopen(taskname".inp", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

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