Codeforces 600 E

E - Lomsat gelral

思路1：

树上启发式合并

代码：

#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pi acos(-1.0)
#define LL long long
//#define mp make_pair
#define pb push_back
#define ls rt<<1, l, m
#define rs rt<<1|1, m+1, r
#define ULL unsigned LL
#define pll pair<LL, LL>
#define pii pair<int, int>
#define piii pair<int,pii>
#define mem(a, b) memset(a, b, sizeof(a))
#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);
//head

const int N = 1e5 + 5;
int color[N], sz[N], bs[N], mx = 0;
LL ans[N], t = 0;
vector<int>g[N];
map<int, int>mp;
void dfs(int o, int u) {
    sz[u] = 1;
    for (int v : g[u]) {
        if(v != o) {
            dfs(u, v);
            sz[u] += sz[v];
            if(sz[v] > sz[bs[u]]) bs[u] = v;
        }
    }
}
void ADD(int o, int u) {
    mp[color[u]] ++;
    if(mp[color[u]] > mx) t = color[u], mx = mp[color[u]];
    else if(mp[color[u]] == mx) t += color[u];
    for (int v : g[u]) {
        if(v != o) {
            ADD(u, v);
        }
    }
}
void DFS(int o, int u) {
    for (int v : g[u]) {
        if(v != o && v != bs[u]) {
            DFS(u, v);
            mp.clear();
            mx = 0;
            t = 0;
        }
    }
    if(bs[u]) DFS(u, bs[u]);
    for (int v : g[u]) {
        if(v != o && v != bs[u]) {
            ADD(u, v);
        }
    }
    mp[color[u]] ++;
    if(mp[color[u]] > mx) t = color[u], mx = mp[color[u]];
    else if(mp[color[u]] == mx) t += color[u];
    ans[u] = t;
}
int main() {
    int n, u, v;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) scanf("%d", &color[i]);
    for (int i = 1; i < n; i++) {
        scanf("%d %d", &u, &v);
        g[u].pb(v);
        g[v].pb(u);
    }
    dfs(0, 1);
    DFS(0, 1);
    for (int i = 1; i <= n; i++) printf("%lld%c", ans[i], " 
"[i==n]);
    return 0;
}

 思路2：

dfs序+分块 求区间众数和

代码：

#pragma GCC optimize(2)
#pragma GCC optimize(3)
#pragma GCC optimize(4)
#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pi acos(-1.0)
#define LL long long
//#define mp make_pair
#define pb push_back
#define ls rt<<1, l, m
#define rs rt<<1|1, m+1, r
#define ULL unsigned LL
#define pll pair<LL, LL>
#define pli pair<LL, int>
#define pii pair<int, int>
#define piii pair<pii, int>
#define mem(a, b) memset(a, b, sizeof(a))
#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);
//head

const int N = 1e5 + 10;
const int M = 500;
vector<int> g[N];
vector<int> pos[N];
int a[N], t[N], in[N], out[N], cnt[N], bl[N], blo, tot = 0, n;
int f[M][M];
LL fres[M][M];
void dfs(int o, int u) {
    in[u] = ++tot;
    t[tot] = a[u];
    for (int v : g[u]) {
        if(v != o) {
            dfs(u, v);
        }
    }
    out[u] = tot;
}
void init(int x) {
    for (int i = 1; i <= n; i++) cnt[i] = 0;
    int ans = 0, c = 0;
    LL res = 0;
    for (int  i = (x-1)*blo + 1; i <= n; i++) {
        cnt[t[i]]++;
        if(cnt[t[i]] > c) {
            res = ans = t[i];
            c = cnt[t[i]];
        }
        else if(cnt[t[i]] == c) {
            ans = t[i];
            res += t[i];
        }
        f[x][bl[i]] = ans;
        fres[x][bl[i]] = res;
    }
}
int cal(int l, int r, int x) {
    if(l > r) return 0;
    return upper_bound(pos[x].begin(), pos[x].end(), r) - lower_bound(pos[x].begin(), pos[x].end(), l);
}
LL query(int l, int r) {
    LL res = 0;
    int ans = 0, c = 0;
    if(bl[l] == bl[r]) {
        vector<int> vc;
        for (int i = l; i <= r; i++) vc.pb(t[i]);
        sort(vc.begin(), vc.end());
        vc.erase(unique(vc.begin(), vc.end()), vc.end());
        for (int i = 0; i < vc.size(); i++) {
            int tot = cal(l, r, vc[i]);
            if(tot > c) {
                res = ans = vc[i];
                c = tot;
            }
            else if(tot == c) {
                ans = vc[i];
                res += vc[i];
            }
        }
        return res;
    }
    ans = f[bl[l]+1][bl[r]-1];
    res = fres[bl[l]+1][bl[r]-1];
    int L = bl[l]*blo+1, R = (bl[r]-1)*blo;
    c = cal(L, R, ans);
    vector<int> vc;
    for (int i = l; i <= bl[l]*blo; i++) vc.pb(t[i]);
    for (int i = (bl[r]-1)*blo + 1; i <= r; i++) vc.pb(t[i]);
    sort(vc.begin(), vc.end());
    vc.erase(unique(vc.begin(), vc.end()), vc.end());
    for (int i = 0; i < vc.size(); i++) {
        int tot = cal(l, r, vc[i]);
        if(tot > c) {
            res = ans = vc[i];
            c = tot;
        }
        else if(tot == c) {
            ans = vc[i];
            res += vc[i];
        }
    }
    return res;
}
int main() {
    int u, v;
    scanf("%d", &n);
    blo = sqrt(n);
    for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
    for (int i = 1; i < n; i++) {
        scanf("%d %d", &u, &v);
        g[u].pb(v);
        g[v].pb(u);
    }
    dfs(1, 1);
    for (int i = 1; i <= n; i++) bl[i] = (i-1)/blo + 1;
    for (int i = 1; i <= bl[n]; i++) init(i);
    for (int i = 1; i <= n; i++) pos[t[i]].pb(i);
    for (int i = 1; i <= n; i++) printf("%lld%c", query(in[i], out[i]), " 
"[i==n]);
    return 0;
}