Codeforces 191C Fools and Roads(树链拆分)

#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;
const int maxn = 1e5 + 5;

int N, Q, ne, first[maxn], f[maxn], jump[maxn * 2];
int id, idx[maxn], top[maxn], far[maxn], son[maxn], dep[maxn], cnt[maxn];

struct Edge {
int u, v;
void set (int u, int v) {
this->u = u;
this->v = v;
}
}ed[maxn * 2];

void dfs (int u, int pre, int d) {
far[u] = pre;
dep[u] = d;
cnt[u] = 1;
son[u] = 0;

for (int i = first[u]; i + 1; i = jump[i]) {
int v = ed[i].v;
if (v == pre)
continue;
dfs(v, u, d + 1);
cnt[u] += cnt[v];
if (cnt[son[u]] < cnt[v])
son[u] = v;
}
}

void dfs(int u, int rot) {
top[u] = rot;
idx[u] = ++id;
if (son[u])
dfs(son[u], rot);
for (int i = first[u]; i + 1; i = jump[i]) {
int v = ed[i].v;
if (v == far[u] || v == son[u])
continue;
dfs(v, v);
}
}

inline void add_Edge(int u, int v) {
ed[ne].set(u, v);
jump[ne] = first[u];
first[u] = ne++;
}

void init () {
int u, v;
ne = id = 0;
memset(first, -1, sizeof(first));
scanf("%d", &N);
for (int i = 1; i < N; i++) {
scanf("%d%d", &u, &v);
add_Edge(u, v);
add_Edge(v, u);
}
dfs(1, 0, 0);
dfs(1, 1);
for (int i = 0; i < N - 1; i++) {
int t = i * 2;
if (dep[ed[t].u] < dep[ed[t].v])
swap(ed[t].u, ed[t].v);
}
}

inline void add (int l, int r) {
f[l]++, f[r + 1]--;
}

void solve (int u, int v) {
int p = top[u], q = top[v];
while (p != q) {
if (dep[p] < dep[q]) {
swap(p, q);
swap(u, v);
}
add(idx[p], idx[u]);

u = far[p];
p = top[u];
}

if (u == v)
return;

if (dep[u] > dep[v])
swap(u, v);
add(idx[son[u]], idx[v]);
}

int main () {
init();

scanf("%d", &Q);
int u, v;
while (Q--) {
scanf("%d%d", &u, &v);
solve(u, v);
}

int mv = 0;
for (int i = 1; i <= N; i++) {
mv += f[i];
f[i] = mv;
}

printf("%d", f[idx[ed[0].u]]);
for (int i = 1; i < N - 1; i++)
printf(" %d", f[idx[ed[i*2].u]]);
printf("\n");
return 0;
}