Submission #187683

#	Time	Username	Problem	Language	Result	Execution time	Memory
187683		dndhk	Election Campaign (JOI15_election_campaign)	C++14	100 / 100	676 ms	61896 KiB

election_campaign

#include <bits/stdc++.h>

#define pb push_back

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAX_N = 100000;
const ll INFLL = 10000;
const int MAX_K = 20;
int N, M;
vector<int> gp[MAX_N+1];
int lv[MAX_N+1], p[MAX_N+1], up[MAX_N+1][MAX_K+1];
vector<pii> vt[MAX_N+1];

void dfs(int x){
	up[x][0] = p[x];
	for(int i=1; i<MAX_K; i++)	up[x][i] = up[up[x][i-1]][i-1];
	for(int i=0; i<MAX_K; i++)	vt[up[x][i]].pb({x, i});
	for(int i : gp[x]){
		if(i==p[x])	continue;
		lv[i] = lv[x]+1;
		p[i] = x;
		dfs(i);
	}
}

int lca(int x, int y){
	for(int i=MAX_K-1; i>=0; i--){
		if(lv[up[x][i]]>=lv[y])	x = up[x][i];
		if(lv[up[y][i]]>=lv[x])	y = up[y][i];
	}
	if(x==y)	return x;
	for(int i=MAX_K-1; i>=0; i--){
		if(up[x][i]!=up[y][i])	{
			x = up[x][i];
			y = up[y][i];
		}
	}
	return up[x][0];
}

int dist(int x, int y){
	int ret = 0;
	for(int i=MAX_K-1; i>=0; i--){
		if(lv[up[x][i]]>=lv[y])	{
			x = up[x][i];
			ret+=(1<<i);
		}
		if(lv[up[y][i]]>=lv[x])	{
			y = up[y][i];
			ret+=(1<<i);
		}
	}
	if(x==y)	return ret;
	for(int i=MAX_K-1; i>=0; i--){
		if(up[x][i]!=up[y][i])	{
			x = up[x][i];
			y = up[y][i];
			ret+=(1<<(i+1));
		}
	}
	return ret+2;
}

int upk(int x, int y){
	for(int i=MAX_K-1; i>=0; i--){
		if(y>=(1<<i)){
			x = up[x][i];
			y-=(1<<i);
		}
	}
	return x;
}

struct Q{
	int a, b, c;
};
vector<Q> query[MAX_N+1];
int dp1[MAX_N+1], dp2[MAX_N+1], dp3[MAX_N+1];
int cost[MAX_N+1][MAX_K+1];

void calc(int x, int y){
	if(y==0){
		cost[x][y] = dp2[x]-dp1[x];
	}else{
		cost[x][y] = cost[x][y-1] + cost[up[x][y-1]][y-1];
	}
}

int calc2(int x, int y){
	int ret = 0;
	for(int i=MAX_K-1; i>=0; i--){
		if(lv[up[x][i]]>=lv[y]){
			ret += cost[x][i];
			x = up[x][i];
		}
	}
	return ret;
}

void dfs2(int x){
	for(int i : gp[x]){
		if(i==p[x])	continue;
		dfs2(i);
		dp2[x]+=dp1[i];
	}
	for(pii p : vt[x]){
		calc(p.first, p.second);
	}
	dp3[x] = 0;
	for(Q q : query[x]){
		int sum = dp2[x];
		if(q.a!=x)	sum+=calc2(q.a, x);
		if(q.b!=x)	sum+=calc2(q.b, x);
		dp3[x] = max(dp3[x], sum+q.c);
	}
	dp1[x] = max(dp2[x], dp3[x]);

}

int main(){
	scanf("%d", &N);
	for(int i=1; i<N; i++){
		int a, b; scanf("%d%d", &a, &b);
		gp[a].pb(b); gp[b].pb(a);
	} 
	lv[1] = 1;dfs(1);
	scanf("%d", &M);
	for(int i=1; i<=M; i++){
		int a, b, c; scanf("%d%d%d", &a, &b, &c);
		query[lca(a, b)].pb({a, b, c});
	}
	dfs2(1);
	cout<<dp1[1];
	return 0;
}

Compilation message (stderr)

election_campaign.cpp: In function 'int main()':
election_campaign.cpp:126:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &N);
  ~~~~~^~~~~~~~~~
election_campaign.cpp:128:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   int a, b; scanf("%d%d", &a, &b);
             ~~~~~^~~~~~~~~~~~~~~~
election_campaign.cpp:132:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &M);
  ~~~~~^~~~~~~~~~
election_campaign.cpp:134:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   int a, b, c; scanf("%d%d%d", &a, &b, &c);
                ~~~~~^~~~~~~~~~~~~~~~~~~~~~

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