/**
____ ____ ____ ____ ____ ____
||l |||e |||i |||n |||a |||d ||
||__|||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|/__\|
**/
#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
typedef long long ll;
void speed()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
}
const int maxn = 1e5 + 10;
const ll mod = 1e9 + 7;
int n, q;
int heavy[maxn], ch_idx[maxn], ch_pos[maxn], ch_head[maxn];
int par[maxn], depth[maxn], sub[maxn], strong[maxn];
ll dp[maxn][2], dis[maxn];
vector < pair < int, ll > > g[maxn];
void dfs(int v)
{
heavy[v] = -1;
strong[v] = -1;
for (pair < int, ll > nb : g[v])
{
if (nb.first == par[v])
continue;
depth[nb.first] = depth[v] + 1;
dfs(nb.first);
if (heavy[v] == -1 || sub[nb.first] > sub[heavy[v]])
heavy[v] = nb.first;
if (dp[nb.first][0] + nb.second >= dp[v][0])
{
dp[v][1] = dp[v][0];
dp[v][0] = dp[nb.first][0] + nb.second;
strong[v] = nb.first;
}
else if (dp[nb.first][0] + nb.second > dp[v][1])
{
dp[v][1] = dp[nb.first][0] + nb.second;
}
}
}
ll ans = 0;
vector < int > ver;
vector < pair < ll, ll > > st;
set < int > weak;
vector < pair < ll, ll > > tree;
vector < ll > lazy;
void build_tree(int root, int left, int right)
{
if (left == right)
{
tree[root] = st[left];
return;
}
int mid = (left + right) / 2;
build_tree(root * 2, left, mid);
build_tree(root * 2 + 1, mid + 1, right);
}
void build_chain()
{
for (int i = 0; i < ver.size(); i ++)
{
st.push_back({dp[ver[i]][0], dp[ver[i]][1]});
if (i != (int)(ver.size()) - 1)
{
if (strong[ver[i]] != ver[i + 1])
weak.insert(i);
}
}
tree.resize(ver.size() * 4);
lazy.resize(ver.size() * 4);
build_tree(1, 0, (int)st.size() - 1);
}
void push_lazy(int root, int left, int right)
{
///if (lazy[root].first == lazy[root].second && lazy[root].first == 0)
if (left == right)
{
tree[root].first += lazy[root];
}
else
{
lazy[root * 2] += lazy[root];
lazy[root * 2 + 1] += lazy[root];
}
lazy[root] = 0;
}
pair < ll, ll > get_node(int root, int left, int right, int idx)
{
///cout << left << " " << right << " " << root << " " << idx << " " << endl;
if (lazy[root] != 0)
push_lazy(root, left, right);
if (left == right)
return tree[root];
int mid = (left + right) / 2;
if (idx <= mid)
return get_node(root * 2, left, mid, idx);
return get_node(root * 2 + 1, mid + 1, right, idx);
}
void set_node(int root, int left, int right, int idx, pair < ll,ll > val)
{
///cout << root << " " << left << " " << right << endl;
if (lazy[root] != 0)
push_lazy(root, left, right);
if (left == right)
{
tree[root] = val;
return;
}
int mid = (left + right) / 2;
if (idx <= mid)
set_node(root * 2, left, mid, idx, val);
else
set_node(root * 2 + 1, mid + 1, right, idx, val);
}
void update_range(int root, int left, int right, int qleft, int qright, ll val)
{
if (lazy[root] != 0)
push_lazy(root, left, right);
if (left == qleft && right == qright)
{
lazy[root] = val;
push_lazy(root, left, right);
return;
}
int mid = (left + right) / 2;
if (qright <= mid)
update_range(root * 2, left, mid, qleft, qright, val);
else if (qleft > mid)
update_range(root * 2 + 1, mid + 1, right, qleft, qright, val);
else
{
update_range(root * 2, left, mid, qleft, mid, val);
update_range(root * 2 + 1, mid + 1, right, mid + 1, qright, val);
}
/**if (left > qright || right < qleft)
return;
if (left >= qleft && right <= qright)
{
lazy[root] = val;
push_lazy(root, left, right);
return;
}
int mid = (left + right) / 2;
update_range(root * 2, left, mid, qleft, qright, val);
update_range(root * 2 + 1, mid + 1, right, qleft, qright, val);*/
}
pair < ll, ll > get_element(int v)
{
///cout << "get_element query" << v << endl;
return get_node(1, 0, (int)(ver.size()) - 1, ch_pos[v]);
}
void set_element(int v, pair < ll, ll > val)
{
//cout << "set_element query" << v << endl;
set_node(1, 0, (int)(ver.size()) - 1, ch_pos[v], val);
}
void update_path(int lf, int rf, ll val)
{
update_range(1, 0, (int)(ver.size()) - 1, lf, rf, val);
}
int ch_st[maxn], ch_en[maxn];
int nxt;
void hld(int v, int head)
{
ch_pos[v] = ver.size();
ver.push_back(v);
ch_head[v] = head;
ch_idx[v] = nxt;
if (v == head)
ch_st[nxt] = ch_pos[v];
ch_en[nxt] = ch_pos[v];
if (heavy[v] != -1)
{
hld(heavy[v], head);
}
for (pair < int, ll > nb : g[v])
{
if (nb.first == par[v] || nb.first == heavy[v])
continue;
nxt ++;
hld(nb.first, nb.first);
}
}
void update(int v, ll d)
{
ll cur = dp[v][0];
dis[v] += d;
while(true)
{
if (v == 0)
break;
cur = cur + dis[v];
///cout << v << " :: " << cur << endl;
if (strong[par[v]] == v)
{
ans = ans + cur - dp[par[v]][0];
ans = (ans + mod) % mod;
dp[par[v]][0] = cur;
v = par[v];
continue;
}
if (cur <= dp[par[v]][1])
break;
if (cur <= dp[par[v]][0])
{
ans = ans + cur - dp[par[v]][1];
ans = (ans + mod) % mod;
dp[par[v]][1] = cur;
break;
}
ans = ans + cur - dp[par[v]][1];
ans = (ans + mod) % mod;
dp[par[v]][1] = dp[par[v]][0];
dp[par[v]][0] = cur;
strong[par[v]] = v;
v = par[v];
}
/**cout << "------------" << endl;
for (int i = 0; i < n; i ++)
cout << dp[i][0] << " " << dp[i][1] << endl;
cout << "------------" << endl;*/
}
void update_edge(int v, ll d)
{
dis[v] += d;
pair < ll, ll > cur, aft;
while(true)
{
///cout << "here " << v << endl;
if (v == 0)
break;
if (ch_head[v] == v)
{
cur = get_element(v);
aft = get_element(par[v]);
if (strong[par[v]] == v)
{
ans = (ans + cur.first + dis[v] - aft.first) % mod;
aft.first = cur.first + dis[v];
set_element(par[v], aft);
v = par[v];
}
else
{
if (cur.first + dis[v] <= aft.second)
break;
if (cur.first + dis[v] <= aft.first)
{
ans = (ans + cur.first + dis[v] - aft.second) % mod;
aft.second = cur.first + dis[v];
///cout << v << " " << par[v] << " " << aft.first << " " << aft.second << endl;
set_element(par[v], aft);
break;
}
ans = (ans + cur.first + dis[v] - aft.second) % mod;
if (strong[par[v]] == ver[ch_pos[par[v]] + 1])
weak.insert(ch_pos[par[v]]);
strong[par[v]] = v;
aft.second = aft.first;
aft.first = cur.first + dis[v];
set_element(par[v], aft);
v = par[v];
continue;
}
}
else
{
int pos = ch_pos[ch_head[v]];
if (!weak.empty())
{
set < int > :: iterator it = weak.lower_bound(ch_pos[v]);
if (it != weak.begin())
{
it = prev(it);
pos = max(*it + 1, pos);
}
}
/**for (int x : ch[ch_idx[v]].weak)
cout << x << " ";
cout << endl;*/
///cout << pos << " " << ch_pos[v] << endl;
if (pos == ch_pos[v])
{
cur = get_element(v);
aft = get_element(par[v]);
if (cur.first + dis[v] <= aft.second)
break;
if (cur.first + dis[v] <= aft.first)
{
ans = (ans + cur.first + dis[v] - aft.second) % mod;
aft.second = cur.first + dis[v];
set_element(par[v], aft);
continue;
}
strong[par[v]] = v;
weak.erase(pos - 1);
ans = (ans + cur.first + dis[v] - aft.second) % mod;
aft.second = aft.first;
aft.first = cur.first + dis[v];
set_element(par[v], aft);
pair < ll, ll > sad = get_element(par[v]);
///cout << sad.first << " " << sad.second << endl;
v = par[v];
continue;
}
else
{
cur = get_element(v);
aft = get_element(par[v]);
ll diff = cur.first + dis[v] - aft.first;
ans = (ans + diff * (ch_pos[v] - pos)) % mod;
update_path(pos, ch_pos[v] - 1, diff);
v = ver[pos];
continue;
}
}
}
}
void solve()
{
cin >> n;
for (int i = 1; i < n; i ++)
cin >> par[i];
for (int i = 1; i < n; i ++)
{
cin >> dis[i];
g[par[i]].push_back({i, dis[i]});
}
par[0] = -1;
dfs(0);
hld(0, 0);
/**for (int i = 0; i < size(); i ++)
{
cout << i << " : ";
for (int v : ch[i].ver)
cout << v << " ";
cout << endl;
}*/
build_chain();
for (int j = 0; j < (int)ver.size() - 1; j ++)
{
if (strong[ver[j]] != ver[j + 1] && ch_idx[ver[j]] == ch_idx[ver[j + 1]])
weak.insert(j);
}
cin >> q;
for (int i = 0; i < n; i ++)
ans = (ans + dp[i][0] + dp[i][1]) % mod;
cout << ans << endl;
///get_element(1);
///get_element(0);
///set_element(par[1], {1, 0});
///get_element(par[1]);
///exit(0);
for (int i = 0; i < q; i ++)
{
///if (i % 10000 == 0)
///cout << "YEP" << endl;
int v;
ll d;
cin >> v >> d;
///update(v, d);
update_edge(v, d);
cout << ans << endl;
}
}
int main()
{
///freopen("input.txt", "r", stdin);
speed();
solve();
return 0;
}
Compilation message
arboras.cpp: In function 'void build_chain()':
arboras.cpp:83:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
83 | for (int i = 0; i < ver.size(); i ++)
| ~~^~~~~~~~~~~~
arboras.cpp: In function 'void update_edge(int, ll)':
arboras.cpp:361:33: warning: variable 'sad' set but not used [-Wunused-but-set-variable]
361 | pair < ll, ll > sad = get_element(par[v]);
| ^~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
6 ms |
2900 KB |
Output is correct |
| 2 |
Correct |
2 ms |
2900 KB |
Output is correct |
| 3 |
Correct |
2 ms |
2900 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
204 ms |
25992 KB |
Output is correct |
| 2 |
Correct |
99 ms |
25384 KB |
Output is correct |
| 3 |
Correct |
91 ms |
26068 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
5072 ms |
26308 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
6 ms |
2900 KB |
Output is correct |
| 2 |
Correct |
2 ms |
2900 KB |
Output is correct |
| 3 |
Correct |
2 ms |
2900 KB |
Output is correct |
| 4 |
Correct |
204 ms |
25992 KB |
Output is correct |
| 5 |
Correct |
99 ms |
25384 KB |
Output is correct |
| 6 |
Correct |
91 ms |
26068 KB |
Output is correct |
| 7 |
Execution timed out |
5072 ms |
26308 KB |
Time limit exceeded |
| 8 |
Halted |
0 ms |
0 KB |
- |
