new file: P2982.cpp

P2982.cpp

@@ -0,0 +1,64 @@
+#include<bits/stdc++.h>
+#define int long long
+using namespace std;
+int n;
+vector<int> fri[100005];
+int p[100005];
+int dfn[100005];
+int cnt[100005];
+int nowdfn;
+struct SEG{
+    int num[400005], lt[400005];
+    void pd(int now, int nl, int nr) {
+        int nmid = (nl + nr) >> 1;
+        num[now * 2] += lt[now] * (nmid - nl + 1);
+        num[now * 2 + 1] += lt[now] * (nr - nmid);
+        lt[now * 2] += lt[now];
+        lt[now * 2 + 1] += lt[now];
+        lt[now] = 0;
+    }
+    void pu(int now) {num[now] = num[now * 2] + num[now * 2 + 1];}
+    void add(int now, int nl, int nr, int l, int r, int nn) {
+        if(nl > r || nr < l) return;
+        if(l <= nl && nr <= r) {
+            num[now] += nn * (nr - nl + 1);
+            lt[now] += nn;
+            return;
+        }
+        int nmid = (nl + nr) >> 1;
+        add(now * 2, nl, nmid, l, r, nn);
+        add(now * 2 + 1, nmid + 1, nr, l, r, nn);
+        pu(now);
+    }
+    int query(int now, int nl, int nr, int l, int r) {
+        if(nl > r || nr < l) return 0;
+        if(l <= nl && nr <= r) return num[now];
+        int nmid = (nl + nr) >> 1;
+        pd(now, nl, nr);
+        return query(now * 2, nl, nmid, l, r) + query(now * 2 + 1, nmid + 1, nr, l, r);
+    }
+}seg;
+void dfs(int now, int from) {
+    cnt[now] = 1;
+    dfn[now] = ++nowdfn;
+    for(int i : fri[now]) {
+        if(i == from) continue;
+        dfs(i, now);
+        cnt[now] += cnt[i];
+    }
+}
+signed main() {
+    scanf("%lld", &n);
+    for(int i = 1, u, v; i < n; ++i) {
+        scanf("%lld%lld", &u, &v);
+        fri[u].push_back(v);
+        fri[v].push_back(u);
+    }
+    dfs(1, 0);
+    for(int i = 1; i <= n; ++i) {
+        scanf("%lld", &p[i]);
+        printf("%lld\n", seg.query(1, 1, n, dfn[p[i]], dfn[p[i]]));
+        seg.add(1, 1, n, dfn[p[i]], dfn[p[i]] + cnt[p[i]] - 1, 1);
+    }
+    return 0;
+}