Submission #427370

#	Time	Username	Problem	Language	Result	Execution time	Memory
427370		cpp219	Traffic (IOI10_traffic)	C++14	50 / 100	668 ms	262148 KiB

traffic

#pragma GCC optimization "O2"
#pragma GCC optimization "unroll-loop"
#pragma GCC target ("avx2")

#include <bits/stdc++.h>
#define ll int
#define ld long double
#define fs first
#define sc second
using namespace std;
const ll N = 1e6 + 9;
const ll inf = 2e9 + 7;
const ll Log2 = 20;
typedef pair<ll,ll> LL;
vector<ll> g[N];
ll n,a[N],mn = inf,chosen,child[N],InitChild[N],sum;
set<LL> s[N];

void DFSinit(ll u,ll p){
    child[u] = a[u];
    for (auto i : g[u]){
        if (i == p) continue;
        DFSinit(i,u); child[u] += child[i];
        s[u].insert({child[i],i});
    }
    InitChild[u] = child[u];
}

void DFS(ll u,ll p){
    if (!s[u].empty()){
        LL now = *s[u].rbegin(),rm = {sum - child[u],-1};
        now = max(now,rm);
        if (now.fs < mn) mn = now.fs,chosen = u;
    }
    for (auto i : g[u]){
        if (i == p) continue;
        s[u].erase({child[i],i}); s[i].insert({sum - child[i],u});
        //cout<<child[i]<<" "<<i; exit(0);
        child[u] = sum - child[i]; child[i] = sum;
        DFS(i,u);
    }
    if (p >= 0){
        child[u] = InitChild[u];
        s[p].insert({child[u],u}); s[u].erase({child[p],p});
        child[p] = InitChild[p];
    }
}

ll LocateCentre(ll sz,ll P[],ll X[],ll Y[]){
    n = sz;
    for (ll i = 0;i < n;i++) a[i] = P[i],sum += a[i];
    for (ll i = 0;i < n - 1;i++){
        g[X[i]].push_back(Y[i]); g[Y[i]].push_back(X[i]);
    }
    DFSinit(0,-1); DFS(0,-1);
    return chosen;
}
/*
ll sz,X[N],Y[N],P[N];

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    #define task "test"
    if (fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        //freopen(task".out", "w", stdout);
    }
    cin>>sz;
    for (ll i = 0;i < sz;i++) cin>>P[i];
    for (ll i = 0;i < sz - 1;i++) cin>>X[i]>>Y[i];
    cout<<LocateCentre(sz,P,X,Y);
}
*/

Compilation message (stderr)

traffic.cpp:1: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    1 | #pragma GCC optimization "O2"
      | 
traffic.cpp:2: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    2 | #pragma GCC optimization "unroll-loop"
      |

• Subtask 1: 25 / 25
• Subtask 2: 0 / 25
• Subtask 3: 25 / 25
• Subtask 4: 0 / 25