Blog of RuSun

\begin {array}{c} \mathfrak {One Problem Is Difficult} \\\\ \mathfrak {Because You Don't Know} \\\\ \mathfrak {Why It Is Diffucult} \end {array}

P4211 [LNOI2014]LCA

P4211 [LNOI2014]LCA

拆贡献,从小到大枚举 $i$ ,在根到 $i$ 的链上增加贡献,查询时查询根到 $i$ 的贡献和。

查看代码
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#include <cstdio>
#include <vector>
#define eb emplace_back
using namespace std;
template <class Type>
void read (Type &x)
{
char c;
bool flag = false;
while ((c = getchar()) < '0' || c > '9')
if (c == '-') flag = true;
x = c - '0';
while ((c = getchar()) >= '0' && c <= '9')
x = (x << 3) + (x << 1) + c - '0';
if (flag) x = ~x + 1;
}
template <class Type, class ...Rest>
void read (Type &x, Rest &...y) { read(x), read(y...); }
template <class Type>
void write (Type x)
{
if (x < 0) putchar('-'), x = ~x + 1;
if (x > 9) write(x / 10);
putchar('0' + x % 10);
}
typedef long long LL;
const int N = 5e4 + 10, mod = 201314;
vector <int> g[N];
int n, m, ans[N], p[N], d[N], sz[N];
int son[N], top[N], stmp, dfn[N];
struct Query { int op, id, z; Query (int _op, int _id, int _z) : op(_op), id(_id), z(_z) { } };
vector <Query> q[N];
struct Node { LL s, t; } tr[N << 2];
void modify (int l, int r, int L = 1, int R = n, int x = 1)
{
tr[x].s += (min(r, R) - max(l, L) + 1);
if (L >= l && R <= r) return void(++tr[x].t);
int mid = L + R >> 1;
if (l <= mid) modify(l, r, L, mid, x << 1);
if (r > mid) modify(l, r, mid + 1, R, x << 1 | 1);
}
LL query (int l, int r, int L = 1, int R = n, int x = 1)
{
if (L >= l && R <= r) return tr[x].s;
int mid = L + R >> 1;
LL res = (min(r, R) - max(l, L) + 1) * tr[x].t;
if (l <= mid) res += query(l, r, L, mid, x << 1);
if (r > mid) res += query(l, r, mid + 1, R, x << 1 | 1);
return res;
}
void dfs1 (int u)
{
sz[u] = 1;
for (int v : g[u])
{
d[v] = d[u] + 1;
dfs1(v);
sz[u] += sz[v];
if (sz[v] > sz[son[u]]) son[u] = v;
}
}
void dfs2 (int u, int t)
{
top[u] = t;
dfn[u] = ++stmp;
if (!son[u]) return;
dfs2(son[u], t);
for (int v : g[u])
if (v ^ p[u] && v ^ son[u]) dfs2(v, v);
}
void modifyPath (int x)
{
for (; top[x] ^ 1; x = p[top[x]])
modify(dfn[top[x]], dfn[x]);
modify(1, dfn[x]);
}
LL queryPath (int x)
{
LL res = 0;
for (; top[x] ^ 1; x = p[top[x]])
res += query(dfn[top[x]], dfn[x]);
res += query(1, dfn[x]);
return res;
}
int main ()
{
read(n, m);
for (int i = 2; i <= n; ++i)
read(p[i]), g[++p[i]].eb(i);
dfs1(1), dfs2(1, 1);
for (int i = 1, l, r, z; i <= m; ++i)
{
read(l, r, z), ++l, ++r, ++z;
q[l - 1].eb(-1, i, z), q[r].eb(1, i, z);
}
for (int i = 1; i <= n; ++i)
{
modifyPath(i);
for (Query j : q[i])
ans[j.id] += j.op * queryPath(j.z);
}
for (int i = 1; i <= m; ++i)
write(ans[i] % mod), puts("");
return 0;
}