Submission #597275

#	Time	Username	Problem	Language	Result	Execution time	Memory
597275		Hacv16	Arboras (RMI20_arboras)	C++17	24 / 100	5010 ms	106872 KiB

arboras

#include<bits/stdc++.h>
using namespace std;

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

const int MAX = 2e6 + 15;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;

#define pb push_back
#define sz(x) (int) x.size()
#define fr first
#define sc second
#define mp make_pair
#define all(x) x.begin(), x.end()
#define dbg(x) cout << #x << ": " << "[ " << x << " ]\n"

ll n, q, p[MAX], wg[MAX], dp[MAX][2], use[MAX][2], ans; 
vector<int> adj[MAX], weight[MAX];

void dfs(int u){
    for(int i = 0; i < sz(adj[u]); i++){
        int v = adj[u][i], w = weight[u][i];
        dfs(v);

        if(dp[v][0] + w > dp[u][0]){
            dp[u][1] = dp[u][0];
            dp[u][0] = dp[v][0] + w;

            use[u][1] = use[u][0];
            use[u][0] = v;

        }else if(dp[v][0] + w > dp[u][1]){
            dp[u][1] = dp[v][0] + w;
            use[u][1] = v;
        }
    }

    ans += dp[u][0] + dp[u][1]; ans %= MOD;
}

void update(int u, int x){ //Update the tree and answer
    wg[u] += x;

    while(u != 0){
        if(use[p[u]][0] == u){
            ans += dp[u][0] + wg[u] - dp[p[u]][0]; 
            dp[p[u]][0] = dp[u][0] + wg[u];

        }else if(dp[u][0] + wg[u] > dp[p[u]][0]){
            ans += dp[p[u]][0] - dp[p[u]][1] + dp[u][0] + wg[u] - dp[p[u]][0];
            dp[p[u]][1] = dp[p[u]][0]; 
            use[p[u]][0] = use[p[u]][1];

            dp[p[u]][0] = dp[u][0] + wg[u];
            use[p[u]][0] = u;

        }else if(dp[u][0] + wg[u] > dp[p[u]][1]){
            ans += dp[u][0] + wg[u] - dp[p[u]][1];
            dp[p[u]][1] = dp[u][0] + wg[u];
            use[p[u]][1] = u;
        }

        ans %= MOD;
        u = p[u];
    }
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); 

    cin >> n;

    for(int i = 1; i < n; i++){
        cin >> p[i];
        adj[p[i]].pb(i);
    }

    for(int i = 1; i < n; i++){
        cin >> wg[i];
        weight[p[i]].pb(wg[i]);
    }

    dfs(0);

    cout << ans << '\n';

    cin >> q;

    while(q--){
        int u, add; cin >> u >> add;
        update(u, add);
        cout << ans << '\n';
    }
    
    return 0;
}

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