「CF600E」Lomsat gelral

Posted 2021-03-24 zsbzsb

传送门
Luogu

解题思路

线段树合并板子题（也可以 dsu on the tree）
好像没什么好讲的，就是要注意开 long long 。

细节注意事项

• 咕咕咕

参考代码

#include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <cctype>
#include <cmath>
#include <ctime>
#define rg register
using namespace std;
template < typename T > inline void read(T& s) {
    s = 0; int f = 0; char c = getchar();
    while (!isdigit(c)) f |= (c == '-'), c = getchar();
    while (isdigit(c)) s = s * 10 + (c ^ 48), c = getchar();
    s = f ? -s : s;
}

typedef long long LL;
const int _ = 100010;

int tot, head[_], nxt[_ << 1], ver[_ << 1];
inline void Add_edge(int u, int v)
{ nxt[++tot] = head[u], head[u] = tot, ver[tot] = v; }

int n, c[_];
int cnt, rt[_], lc[_ << 5], rc[_ << 5];
LL mx[_ << 5], col[_ << 5], ans[_];

inline void pushup(int p) {
    if (mx[lc[p]] > mx[rc[p]]) mx[p] = mx[lc[p]], col[p] = col[lc[p]];
    if (mx[lc[p]] < mx[rc[p]]) mx[p] = mx[rc[p]], col[p] = col[rc[p]];
    if (mx[lc[p]] == mx[rc[p]]) mx[p] = mx[lc[p]], col[p] = col[lc[p]] + col[rc[p]];
}

inline void update(int& p, int x, int l = 1, int r = n) {
    if (!p) p = ++cnt;
    if (l == r) { ++mx[p], col[p] = l; return; }
    int mid = (l + r) >> 1;
    if (x <= mid) update(lc[p], x, l, mid);
    else update(rc[p], x, mid + 1, r);
    pushup(p);
}

inline int merge(int x, int y, int l = 1, int r = n) {
    if (!x || !y) return x + y;
    if (l == r)
        return mx[x] += mx[y], col[x] = l, x;
    int mid = (l + r) >> 1;
    lc[x] = merge(lc[x], lc[y], l, mid);
    rc[x] = merge(rc[x], rc[y], mid + 1, r);
    return pushup(x), x;
}

inline void dfs(int u, int f) {
    for (rg int i = head[u]; i; i = nxt[i]) {
        int v = ver[i]; if (v == f) continue;
        dfs(v, u), rt[u] = merge(rt[u], rt[v]);
    }
    update(rt[u], c[u]), ans[u] = col[rt[u]];
}

int main() {
#ifndef ONLINE_JUDGE
    freopen("in.in", "r", stdin);
#endif
    read(n);
    for (rg int i = 1; i <= n; ++i) read(c[i]), rt[++cnt] = i;
    for (rg int u, v, i = 1; i < n; ++i)
        read(u), read(v), Add_edge(u, v), Add_edge(v, u);
    dfs(1, 0);
    for (rg int i = 1; i <= n; ++i) printf("%lld ", ans[i]);
    return 0;
}

完结撒花 (qwq)