#1172. 小T树

https://sjzezoj.com/submission/45136

S2OJ/1172/1172.cpp

@@ -0,0 +1,140 @@
+#include <cstdio>
+#include <vector>
+
+const int N = 200005;
+
+int n, q, u, v, op, a[N];
+std::vector<int> g[N];
+
+// Heavy Path Decomposition
+int cnt, id[N], rid[N], fa[N], dep[N], son[N], siz[N], top[N];
+void dfs1(int, int);
+void dfs2(int, int);
+void modify_tree(int, int);
+int query_point(int);
+
+// Segment Tree
+void pushdown(int);
+void build(int, int, int);
+void modify(int, int, int, int);
+int query(int, int);
+
+int main() {
+    scanf("%d%d", &n, &q);
+    for (int i = 1; i <= n; i++) {
+        scanf("%d", a + i);
+    }
+    for (int i = 1; i < n; i++) {
+        scanf("%d%d", &u, &v);
+        g[u].push_back(v);
+        g[v].push_back(u);
+    }
+    dfs1(1, 1);
+    dfs2(1, 1);
+    build(1, 1, n);
+    while (q--) {
+        scanf("%d%d", &op, &u);
+        if (op == 1) {
+            scanf("%d", &v);
+            modify_tree(u, v);
+        } else {
+            printf("%d\n", query_point(u));
+        }
+    }
+    return 0;
+}
+
+// === Heavy Path Decomposition ===
+
+void dfs1(int u, int f) {
+    fa[u] = f;
+    dep[u] = dep[f] + 1;
+    siz[u] = 1;
+    for (int v : g[u]) {
+        if (v == f) continue;
+        dfs1(v, u);
+        siz[u] += siz[v];
+        if (siz[son[u]] < siz[v]) son[u] = v;
+    }
+}
+
+void dfs2(int u, int t) {
+    id[u] = ++cnt;
+    rid[cnt] = u;
+    if (!son[u]) return;
+    dfs2(son[u], t);
+    for (int v : g[u]) {
+        if (v == fa[u]) continue;
+        if (v == son[u]) continue;
+        dfs2(v, v);
+    }
+}
+
+inline void modify_tree(int u, int d) {
+    modify(1, id[u], id[u] + siz[u] - 1, d * ((dep[u] & 1) ? 1 : -1));
+}
+
+inline int query_point(int x) {
+    return query(1, id[x]);
+}
+
+// === Segment Tree ===
+
+struct node {
+    int l, r, d;
+
+    node()
+        : l(0), r(0), d(0) {}
+    node(int _l, int _r)
+        : l(_l), r(_r), d(0) {}
+} tr[N << 2];
+
+void pushdown(int u) {
+    node &root = tr[u], &left = tr[u << 1], &right = tr[u << 1 | 1];
+    if (!root.d) return;
+    if (left.l == left.r) {
+        left.d += root.d * ((dep[rid[left.l]] & 1) ? 1 : -1);
+    } else {
+        left.d += root.d;
+    }
+    if (right.l == right.r) {
+        right.d += root.d * ((dep[rid[right.l]] & 1) ? 1 : -1);
+    } else {
+        right.d += root.d;
+    }
+    root.d = 0;
+}
+
+void build(int u, int l, int r) {
+    tr[u] = node(l, r);
+    if (l == r) {
+        tr[u].d = a[rid[l]];
+        return;
+    }
+    int mid = l + r >> 1;
+    build(u << 1, l, mid);
+    build(u << 1 | 1, mid + 1, r);
+}
+
+void modify(int u, int l, int r, int d) {
+    if (l <= tr[u].l && tr[u].r <= r) {
+        if (tr[u].l == tr[u].r) {
+            tr[u].d += d * ((dep[rid[tr[u].l]] & 1) ? 1 : -1);
+        } else {
+            tr[u].d += d;
+        }
+        return;
+    }
+    int mid = tr[u].l + tr[u].r >> 1;
+    pushdown(u);
+    if (l <= mid) modify(u << 1, l, r, d);
+    if (r > mid) modify(u << 1 | 1, l, r, d);
+}
+
+int query(int u, int x) {
+    if (tr[u].l == tr[u].r) return tr[u].d;
+    int mid = tr[u].l + tr[u].r >> 1;
+    pushdown(u);
+    if (x <= mid) return query(u << 1, x);
+    return query(u << 1 | 1, x);
+}