Submission #597236

#	Time	Username	Problem	Language	Result	Execution time	Memory
597236		ThegeekKnight16	Arboras (RMI20_arboras)	C++14	0 / 100	5040 ms	18656 KiB

arboras

#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
const int MAXN = 1e5 + 10;
vector<int> grafo[MAXN];
vector<ll> pesos[MAXN]; 
int indices[MAXN];
int pai[MAXN];
ll dp[MAXN][2]; 
int filho[MAXN][2];
ll modulo = 1e9 + 7;

void dfs(int v)
{
    dp[v][0] = 0LL; dp[v][1] = 0LL; 
    filho[v][0] = -1; filho[v][1] = -1;
    
    for (int i = 0; i < grafo[v].size(); i++)
    {
        int viz = grafo[v][i];
        ll p = pesos[v][i];
        dfs(viz);
        if (dp[viz][0] + p >= dp[v][0])
        {
            dp[v][1] = dp[v][0];
            dp[v][0] = (dp[viz][0] + p);
            filho[v][1] = filho[v][0];
            filho[v][0] = viz;
        }
        else if (dp[viz][0] + p >= dp[v][1]) 
        {
            dp[v][1] = (dp[viz][0] + p);
            filho[v][1] = viz;
        }
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int N;
    cin >> N;
    for (int i = 1; i < N; i++)
    {
        cin >> pai[i];
        grafo[pai[i]].push_back(i);
    }
    for (int i = 1; i < N; i++)
    {
        ll p;
        cin >> p;
        pesos[pai[i]].push_back(p);
        indices[i] = pesos[pai[i]].size()-1;
    }
    int Q;
    cin >> Q;
    dfs(0);
    ll resp = 0;
    for (int i = 0; i < N; i++) {resp += (dp[i][0] + dp[i][1]) % (modulo); resp = resp % modulo;}
    cout << resp;
    for (int q = 1; q <= Q; q++)
    {
        int v;
        ll add;
        cin >> v >> add;
        pesos[pai[v]][indices[v]] += add;
        
        while (v != 0)
        {
            ll p = pesos[pai[v]][indices[v]];
            //cerr << "Estou no " << v << " com add " << add << '\n';
            if (dp[v][0] + p <= dp[pai[v]][1]) {/*cerr << "Nao era grande ent quebrei" << '\n';*/ break;}
            if (v == filho[pai[v]][0])
            {
                //cerr << "Eu era o filho 0";
                if (dp[pai[v]][0] == dp[v][0] + p) {/*cerr << "mas n mudei nada" << '\n';*/ break;}
                //cerr << '\n';
                dp[pai[v]][0] += add;
                resp += (add) % modulo;
                resp = resp % modulo;
            }
            else if (v == filho[pai[v]][1])
            {
                //cerr << "Eu era o filho 1";
                if (dp[pai[v]][1] == dp[v][0] + p) {/*cerr << "mas n mudei nada" << '\n';*/ break;}
                dp[pai[v]][1] += add;
                resp += (add) % modulo;
                resp = resp % modulo;
                if (dp[pai[v]][1] > dp[pai[v]][0])
                {
                    //cerr << " e agr virei 0";
                    swap(filho[pai[v]][0], filho[pai[v]][1]);
                    swap(dp[pai[v]][1], dp[pai[v]][0]);
                }
                //cerr << '\n';
            }
            else
            {
                //cerr << "Eu n era filho, por isso aumentou em " << ((dp[v][0] + p) - dp[pai[v]][1]) << '\n';
                resp += ((dp[v][0] + p) - dp[pai[v]][1]) % modulo;
                resp = resp % modulo;
                if (dp[v][0] + p >= dp[pai[v]][0])
                {
                    dp[pai[v]][1] = dp[pai[v]][0];
                    dp[pai[v]][0] = (dp[v][0] + p);
                    filho[pai[v]][1] = filho[pai[v]][0];
                    filho[pai[v]][0] = v;
                }
                else if (dp[v][0] + p >= dp[pai[v]][1]) 
                {
                  dp[pai[v]][1] = (dp[v][0] + p);
                  filho[pai[v]][1] = v;
                }
            }
            v = pai[v];
        }
        //cerr << '\n';
        cout << '\n' << resp % modulo;
    }
}

Compilation message (stderr)

arboras.cpp: In function 'void dfs(int)':
arboras.cpp:18:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |     for (int i = 0; i < grafo[v].size(); i++)
      |                     ~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 13
• Subtask 3: 0 / 31
• Subtask 4: 0 / 45