Submission #922071

#	Time	Username	Problem	Language	Result	Execution time	Memory
922071		firewater	Election Campaign (JOI15_election_campaign)	C++14	100 / 100	87 ms	27628 KiB

election_campaign

#include<bits/stdc++.h>
#define fs first
#define sn second
#define mp make_pair
#define N 100100
#define ll long long
using namespace std;
ll n,m,ans,x,y,z,w,tot,h[N],f[N],fr[N],sz[N],hs[N],top[N],fa[N],dep[N],dfn[N],low[N],v[N];
vector<pair<pair<ll,ll>,ll> >d[N];
struct rec
{
	ll to,nx;
}e[N<<1];
void addl(ll x,ll y)
{
	e[++tot].to=y;
	e[tot].nx=h[x];
	h[x]=tot;
	return;
}
struct TT
{
	ll sum[N];
	void add(ll y,ll z)
	{
		sum[y]+=z;
		return;
	}
	ll ask(ll l,ll r)
	{
		return sum[l]-(hs[fr[r]]?sum[r+1]:0);
	}
}T;
void dfs(ll x)
{
	sz[x]=1;
	for(ll i=h[x];i;i=e[i].nx){
		ll y=e[i].to;
		if(y==fa[x])continue;
		fa[y]=x;
		dep[y]=dep[x]+1;
		dfs(y);
		sz[x]+=sz[y];
		if(sz[y]>sz[hs[x]])hs[x]=y;
	}
	return;
}
void dfs1(ll x,ll anc)
{
	dfn[x]=++w;
	fr[w]=x;
	top[x]=anc;
	if(hs[x])dfs1(hs[x],anc);
	for(ll i=h[x];i;i=e[i].nx){
		ll y=e[i].to;
		if(y==fa[x]||y==hs[x])continue;
		dfs1(y,y);
	}
	low[x]=w;
	return;
}
ll lca(ll x,ll y)
{
	while(top[x]!=top[y]){
		if(dep[top[x]]<dep[top[y]])swap(x,y);
		x=fa[top[x]];
	}
	return (dep[x]<dep[y]?x:y);
}
ll ask(ll x,ll y)
{
	ll sum=0;
	while(top[x]!=top[y]){
		if(dep[top[x]]<dep[top[y]])swap(x,y);
		if(hs[x])sum+=f[hs[x]];
		sum+=T.ask(dfn[top[x]],dfn[x])-f[top[x]];
		x=fa[top[x]];
	}
	if(dep[x]>dep[y])swap(x,y);
	if(hs[y])sum+=f[hs[y]];
	sum+=T.ask(dfn[x],dfn[y]);
	return sum;
}
bool cmp(ll x,ll y)
{
	return dep[x]>dep[y];
}
int main()
{
	scanf("%lld",&n);
	for(ll i=1;i<n;++i){
		scanf("%lld%lld",&x,&y);
		addl(x,y);
		addl(y,x);
	}
	fa[1]=1;
	dep[1]=1;
	dfs(1);
	dfs1(1,1);
	scanf("%lld",&m);
	for(ll i=1;i<=m;++i){
		scanf("%lld%lld%lld",&x,&y,&z);
		ll u=lca(x,y);
		d[u].push_back(mp(mp(x,y),z));
	}
	for(ll i=1;i<=n;++i)
		v[i]=i;
	sort(v+1,v+1+n,cmp);
	for(ll i=1;i<=n;++i){
		x=v[i];
		if(hs[x])T.add(dfn[x],T.sum[dfn[x]+1]);
		f[x]=ask(x,x);
		for(ll j=0;j<d[x].size();++j){
			f[x]=max(f[x],ask(d[x][j].fs.fs,d[x][j].fs.sn)+d[x][j].sn);
		}
		ans=max(ans,f[x]);
		if(x!=1&&x==top[x])T.add(dfn[fa[x]],f[x]);
	}
	printf("%lld\n",ans);
	return 0;
}

Compilation message (stderr)

election_campaign.cpp: In function 'int main()':
election_campaign.cpp:113:15: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<std::pair<long long int, long long int>, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  113 |   for(ll j=0;j<d[x].size();++j){
      |              ~^~~~~~~~~~~~
election_campaign.cpp:90:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   90 |  scanf("%lld",&n);
      |  ~~~~~^~~~~~~~~~~
election_campaign.cpp:92:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   92 |   scanf("%lld%lld",&x,&y);
      |   ~~~~~^~~~~~~~~~~~~~~~~~
election_campaign.cpp:100:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  100 |  scanf("%lld",&m);
      |  ~~~~~^~~~~~~~~~~
election_campaign.cpp:102:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  102 |   scanf("%lld%lld%lld",&x,&y,&z);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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