97 lines
2.4 KiB
C++
97 lines
2.4 KiB
C++
#include<bits/stdc++.h>
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using namespace std;
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int n, k;
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vector<int> fri[100005];
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int cnt[100005];
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int fa[100005];
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int son[100005];
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int dfn[100005];
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int top[100005];
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int dep[100005];
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int nowdfn;
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struct SEG{
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int num[400005], lt[400005];
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void pu(int now) {
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num[now] = num[now * 2] + num[now * 2 + 1];
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}
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void pd(int now, int nl, int nr) {
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int nmid = (nl + nr) >> 1;
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int l = lt[now];
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num[now * 2] += l * (nmid - nl + 1);
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num[now * 2 + 1] += l * (nr - nmid);
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lt[now * 2] += l;
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lt[now * 2 + 1] += l;
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lt[now] = 0;
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}
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void add(int now, int nl, int nr, int l, int r, int nn) {
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if(nl > r || nr < l) return;
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if(l <= nl && nr <= r) {
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num[now] += nn;
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lt[now] += nn;
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return;
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}
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int nmid = (nl + nr) >> 1;
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add(now * 2, nl, nmid, l, r, nn);
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add(now * 2 + 1, nmid + 1, nr, l, r, nn);
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pu(now);
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}
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int query(int now, int nl, int nr, int l, int r) {
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if(nl > r || nr < l) return 0;
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if(l <= nl && nr <= r) {
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return num[now];
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}
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int nmid = (nl + nr) >> 1;
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pd(now, nl, nr);
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return query(now * 2, nl, nmid, l, r) + query(now * 2 + 1, nmid + 1, nr, l, r);
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}
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}seg;
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void dfs1(int now, int from) {
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cnt[now] = 1;
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for(int i : fri[now]) {
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if(i == from) continue;
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fa[i] = now;
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dep[i] = dep[now] + 1;
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dfs1(i, now);
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cnt[now] += cnt[i];
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if(cnt[son[now]] < cnt[i]) son[now] = i;
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}
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}
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void dfs2(int now, int from) {
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dfn[now] = ++nowdfn;
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top[now] = from;
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if(son[now]) dfs2(son[now], from);
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for(int i : fri[now]) {
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if(i == fa[now] || i == son[now]) continue;
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dfs2(i, i);
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}
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}
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void add(int a, int b) {
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while(top[a] != top[b]) {
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if(dep[top[a]] < dep[top[b]]) swap(a, b);
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seg.add(1, 1, n, dfn[top[a]], dfn[a], 1);
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a = fa[top[a]];
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}
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if(dep[a] < dep[b]) swap(a, b);
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seg.add(1, 1, n, dfn[b], dfn[a], 1);
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}
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int main() {
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scanf("%d%d", &n, &k);
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for(int i = 1, u, v; i < n; ++i) {
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scanf("%d%d", &u, &v);
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fri[u].push_back(v);
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fri[v].push_back(u);
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}
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dfs1(1, -1);
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dfs2(1, 1);
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while(k--) {
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int u, v;
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scanf("%d%d", &u, &v);
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add(u, v);
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}
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int ans = 0;
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for(int i = 1; i <= n; ++i) {
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ans = max(ans, seg.query(1, 1, n, i, i));
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}
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printf("%d\n", ans);
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return 0;
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} |