Codeforces 600 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], " \n"[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]), " \n"[i==n]); return 0; }