CF1092F Tree with Maximum Cost

题目链接：​​传送门​​

是​​这个题​​​的一个变形
就是最小值改成最大值
懒了
直接改了改当时的代码
当时的题解里也有解析

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <complex>
#include <algorithm>
#include <climits>
#define
#define

using namespace std;
struct node {
    int next, to; ll dis;
}edge[A];
int head[A], num_edge;
void add_edge(int from, int to, ll dis) {
    edge[++num_edge].next = head[from];
    edge[num_edge].to = to;
    edge[num_edge].dis = dis;
    head[from] = num_edge;
}
ll siz[A], dis[A], f[A], ans = -9223372036854775807, sum;
int n, a, b;
void dfs(int fr, int fa) {
    for (int i = head[fr]; i; i = edge[i].next) {
        int ca = edge[i].to;
        if (ca == fa) continue;
        dfs(ca, fr);
        siz[fr] += siz[ca];
        dis[fr] += dis[ca] + edge[i].dis * siz[ca];
    }
}
void dd(int fr, int fa) {
    ans = max(ans, f[fr]);
    for (int i = head[fr]; i; i = edge[i].next) {
        int ca = edge[i].to;
        if (ca == fa) continue;
        f[ca] = f[fr] + (sum - siz[ca]) * edge[i].dis - siz[ca] * edge[i].dis;
        dd(ca, fr);
    }
}

int main(int argc, const char *argv[]) {
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> siz[i], sum += siz[i];
    for (int i = 1; i < n; i++) {
        cin >> a >> b;
        add_edge(a, b, 1);
        add_edge(b, a, 1);
    }
    dfs(1, 0); f[1] = dis[1]; dd(1, 0);
    if (ans == -9223372036854775807) puts("0");
    else cout << ans << endl;
}