Submission #34838

#	Time	Username	Problem	Language	Result	Execution time	Memory
34838		sinhriv	Election Campaign (JOI15_election_campaign)	C++14	100 / 100	663 ms	54716 KiB

election_campaign

#include <bits/stdc++.h>

using namespace std;

const int N = 100010;

struct Query{
	int u;
	int v;
	int w;
};

/// tree

int n, m, cnt;
int L[N];
int R[N];
int depth[N];
int jump[N][22];
vector < int > adj[N];

void preDfs(int u, int p = 0){
	L[u] = ++cnt;
	jump[u][0] = p;
	depth[u] = depth[p] + 1;
	for(int i = 1; i < 20; ++i){
		jump[u][i] = jump[jump[u][i - 1]][i - 1];
	}
	for(int v : adj[u]){
		if(v == p) continue;
		preDfs(v, u);
	}
	R[u] = cnt;
}

int lca(int u, int v){
	if(depth[u] < depth[v]) swap(u, v);
	for(int i = 19; i >= 0; --i){
		if(depth[jump[u][i]] >= depth[v]) u = jump[u][i];
	}
	if(u == v) return u;

	for(int i = 19; i >= 0; --i){
		if(jump[u][i] != jump[v][i]){
			u = jump[u][i];
			v = jump[v][i];
		}
	}
	return jump[u][0];
}

int subTree(int u, int x){
	for(int i = 19; i >= 0; --i){
		if(depth[jump[x][i]] > depth[u]){
			x = jump[x][i];
		}
	}
	return x;
}

/// Dp


int f[N];
vector < Query > solve[N];

struct SegmentTree{
	int lazy[N << 3];
	int value[N << 3];

	void push(int x){
		value[x] += lazy[x];
		lazy[x + x] += lazy[x];
		lazy[x + x + 1] += lazy[x];
		lazy[x] = 0;
	}

	#define mid ((l + r) >> 1)

	void update(int x, int l, int r, int u, int v, int val){
		push(x);
		if(l > v || r < u) return;
		if(l >= u && r <= v){
			lazy[x] += val;
			push(x);
			return;
		}
		update(x + x, l, mid, u, v, val);
		update(x + x + 1, mid + 1, r, u, v, val);
		value[x] = value[x + x] + value[x + x + 1];
	}

	int query(int x, int l, int r, int pos){
		if(pos > r || pos < l) return 0;
		if(l == r) return value[x] + lazy[x];
		return lazy[x] + query(x + x, l, mid, pos) + query(x + x + 1, mid + 1, r, pos);
	}
}Smt;

#define value(x) Smt.query(1, 1, n, L[x])

void dfs(int u, int p = 0){
	int tot = 0;
	for(int v : adj[u]){
		if(v == p) continue;
		dfs(v, u);
		tot += f[v];
	}

	f[u] = max(f[u], tot);

	for(auto t : solve[u]){
		int a = t.u, b = t.v;
		if(a == b && a == u){
			f[u] = max(f[u], tot + t.w);
			continue;
		}
		if(b == u) swap(a, b);
		if(a == u){
			int v = subTree(u, b);
			f[u] = max(f[u], tot - f[v] + value(b) + t.w);
			continue;
		}

		int i = subTree(u, a), j = subTree(u, b);
		f[u] = max(f[u], tot - f[i] - f[j] + value(a) + value(b) + t.w);
	}

	for(int v : adj[u]){
		if(v == p) continue;
		Smt.update(1, 1, n, L[v], R[v], tot - f[v]);
	}
	Smt.update(1, 1, n, L[u], L[u], tot);
}

int main(){
	if(fopen("1.inp", "r")){
		freopen("1.inp", "r", stdin);
	}


	scanf("%d", &n);
	for(int i = 1; i < n; ++i){
		int u, v;
		scanf("%d%d", &u, &v);
		adj[u].push_back(v);
		adj[v].push_back(u);
	}

	preDfs(1);

	scanf("%d", &m);
	for(int i = 1; i <= m; ++i){
		int u, v, w;
		scanf("%d%d%d", &u, &v, &w);
		int p = lca(u, v);
		solve[p].push_back({u, v, w});
	}

	dfs(1);
	cout << f[1];

	return 0;
}

Compilation message (stderr)

election_campaign.cpp: In function 'int main()':
election_campaign.cpp:138:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   freopen("1.inp", "r", stdin);
                               ^
election_campaign.cpp:142:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
                 ^
election_campaign.cpp:145:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &u, &v);
                        ^
election_campaign.cpp:152:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &m);
                 ^
election_campaign.cpp:155:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d%d", &u, &v, &w);
                              ^

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