제출 #1241847

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1241847		nibert	트리 (IOI24_tree)	C++20	0 / 100	57 ms	22944 KiB

tree

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

typedef long long ll;

const int MAXN = 200005;

int N;
vector<int> tree[MAXN];
int weight[MAXN];
bool isLeaf[MAXN];
int leafCount[MAXN];

ll globalA = 0, globalB = 0; // total cost = A * L + B * R

void dfs_accumulate(int u) {
    isLeaf[u] = true;
    leafCount[u] = 0;
    for (int v : tree[u]) {
        isLeaf[u] = false;
        dfs_accumulate(v);
        leafCount[u] += leafCount[v];
    }
    if (isLeaf[u]) leafCount[u] = 1;

    int k = leafCount[u];
    if (isLeaf[u]) {
        globalA += 1LL * k * weight[u];
    } else {
        // If k*L > R, then we pay (kL - R) * W[u] = k*W[u]*L - W[u]*R
        // So node contributes: A = k * W[u], B = -W[u]
        globalA += 1LL * k * weight[u];
        globalB -= 1LL * weight[u];
    }
}

void init(vector<int> P, vector<int> W) {
    N = P.size();
    for (int i = 0; i < N; ++i) {
        tree[i].clear();
        isLeaf[i] = false;
    }

    for (int i = 1; i < N; ++i) {
        tree[P[i]].push_back(i);
    }

    for (int i = 0; i < N; ++i) weight[i] = W[i];

    globalA = 0;
    globalB = 0;

    dfs_accumulate(0);
}

ll query(int L, int R) {
    return globalA * L + globalB * R;
}

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