Submission #906176

#	Time	Username	Problem	Language	Result	Execution time	Memory
906176		8pete8	Transport (COCI19_transport)	C++17	0 / 130	1056 ms	26700 KiB

Main

#include<iostream>
#include<stack>
#include<map>
#include<vector>
#include<string>
#include<unordered_map>
#include <queue>
#include<cstring>
#include<float.h>
#include<limits.h>
#include <cassert>
#include<cmath>
#include<set>
#include<algorithm>
#include <iomanip>
#include<numeric> //gcd(a,b)
#include<bitset>
using namespace std;
#define ll long long
#define f first
#define endl "\n"
#define s second
#define pii pair<int,ll>
#define ppii pair<int,pii>
#define vi vector<int>
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define F(n) for(int i=0;i<n;i++)
#define lb lower_bound
#define ub upper_bound
using namespace std;
#define int long long
#define double long double
#define fastio ios::sync_with_stdio(false);cin.tie(NULL);
#pragma GCC optimize ("03,unroll-loops")
const int mod=98765431,mxn=1e5,lg=22,inf=1e18,minf=-1e9,Mxn=100000;
int val[mxn+10],n,sz[mxn+10],ans=0;
vector<pii>adj[mxn+10];
bool del[mxn+10];
struct node{
    int mnpref,sum,mnsuf;
    node operator+(node a)const{
        node ans;
        ans.mnpref=min(mnpref,sum+a.mnpref);
        ans.mnsuf=min(a.mnsuf,a.sum+mnsuf);
        ans.sum=sum+a.sum;
        return ans;
    }
};
node v[mxn+10];
void getsz(int cur,int p){
    sz[cur]=1;
    for(auto i:adj[cur])if(i.f!=p&&!del[i.f])getsz(i.f,cur),sz[cur]+=sz[i.f];
}
int getcen(int cur,int p,int mx){
    for(auto i:adj[cur])if(i.f!=p&&!del[i.f]&&sz[i.f]>mx/2)return getcen(i.f,cur,mx);
    return cur;
}
int cnt=0;
vector<int>deg[mxn+10];
int pos[mxn+10];
void solve(int cur,int p){
    v[cur]=v[cur]+(node){val[cur],val[cur],val[cur]};
    for(auto i:adj[cur]){
        if(i.f!=p&&!del[i.f]){
            v[i.f]=v[cur]+(node){-i.s,-i.s,-i.s};
            solve(i.f,cur);
        }
    }
    deg[cnt].pb(cur);
}
struct fen{
    int fwk[mxn+10];
    void update(int pos,int val){for(int i=pos;i<=n;i+=(i&-i))fwk[i]+=val;}
    int qry(int pos){
        int sum=0;
        for(int i=pos;i>0;i-=(i&-i))sum+=fwk[i];
        return sum;
    }
}t;
bool cmp(pii a,pii b){return a.f<b.f;}
void decomp(int cur){
    getsz(cur,-1);
    int cen=getcen(cur,-1,sz[cur]);
    v[cen].mnpref=v[cen].mnsuf=v[cen].sum=val[cen];
    for(auto i:adj[cen]){
        if(del[i.f])continue;
        v[i.f]=v[cen]+(node){-i.s,-i.s,-i.s};
        solve(i.f,cen);
        cnt++;
    }
    vector<pii>a;
    a.clear();
    for(int i=0;i<cnt;i++)for(auto j:deg[i]){
        if(v[j].mnpref>=0)ans++;
        if(v[j].mnsuf>=0)ans++;
        a.pb({-v[j].mnpref,j});
    }
    sort(all(a));
    //if sum+mnpref-val[node]>=0 sum-val[node]>=-mnpref
    for(int i=0;i<a.size();i++)pos[a[i].s]=i+1;
    for(int i=0;i<cnt;i++){
        for(auto j:deg[i])t.update(pos[j],1);
        for(auto j:deg[i]){
            if(v[j].mnsuf<0ll)continue;
            /*int it=ub(all(a),make_pair(v[j].sum-val[cen],inf),cmp)-a.begin()-1;
            if(it<0)continue;
            ans+=it+1-t.qry(it+1);*/
        }
        for(auto j:deg[i])t.update(pos[j],-1);
        deg[i].clear();
    }
    del[cen]=true;
    for(auto i:adj[cen])if(!del[i.f])decomp(i.f);
}
int32_t main(){
    fastio
    cin>>n;
    for(int i=1;i<=n;i++)cin>>val[i];
    for(int i=0;i<n-1;i++){
        int a,b,w;cin>>a>>b>>w;
        adj[a].pb({b,w});
        adj[b].pb({a,w});
    }
    decomp(1);
    cout<<ans;
}

Compilation message (stderr)

transport.cpp: In function 'void decomp(long long int)':
transport.cpp:102:18: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  102 |     for(int i=0;i<a.size();i++)pos[a[i].s]=i+1;
      |                 ~^~~~~~~~~

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