bzoj2809 [Apio2012]dispatching

# include <stdio.h>
# include <string.h>
# include <algorithm>
// # include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
const int M = 2e5 + 10;
const int mod = 1e9+7;

# define RG register
# define ST static

int n, C, cap;
int c[M], L[M];

int head[M], nxt[M], to[M], tot=0;
inline void add(int u, int v) {
++tot; nxt[tot] = head[u]; head[u] = tot; to[tot] = v;
}
inline void adde(int u, int v) {
add(u, v); add(v, u);
}

int in[M], out[M], DFN=0, dfn[M];
inline void dfs(int x, int fa) {
in[x] = ++DFN; dfn[DFN] = x;
for (int i=head[x]; i; i=nxt[i]) {
if(to[i] == fa) continue;
dfs(to[i], x);
}
out[x] = DFN;
}

int rt[M];
namespace CMT {
const int M = 5e6 + 10;
ll s[M];
int ch[M][2], siz, sz[M];
inline void edt(int &x, int y, int l, int r, int pos) {
x = ++siz; ch[x][0] = ch[y][0], ch[x][1] = ch[y][1];
s[x] = s[y] + pos; sz[x] = sz[y] + 1;
if(l == r) return;
int mid = l+r>>1;
if(pos <= mid) edt(ch[x][0], ch[y][0], l, mid, pos);
else edt(ch[x][1], ch[y][1], mid+1, r, pos);
}
inline ll query(int x, int y, int l, int r, ll res) {
if(res<l) return 0;
if(l == r) return min(res/l, (ll)sz[y]-sz[x]);
ll le = s[ch[y][0]] - s[ch[x][0]];
int mid = l+r>>1;
if(le <= res) return (ll)sz[ch[y][0]] - sz[ch[x][0]] + query(ch[x][1], ch[y][1], mid+1, r, res-le);
else return query(ch[x][0], ch[y][0], l, mid, res);
}
}

int main() {
scanf("%d%d", &n, &C);
for (int i=1, u; i<=n; ++i) {
scanf("%d%d%d", &u, c+i, L+i);
if(u) adde(u, i);
else cap = i;
}
dfs(cap, 0);
for (int i=1; i<=n; ++i)
CMT::edt(rt[i], rt[i-1], 1, 1e9, c[dfn[i]]);
ll ans = 0;
int ps;
for (int i=1; i<=n; ++i) {
ll t = L[i];
t = t * CMT::query(rt[in[i]-1], rt[out[i]], 1, 1e9, C);
if(t > ans) {
ans = t;
ps = i;
}
}
printf("%lld\n", ans);
return 0;
}