P4315 月下“毛景树”

R64759265

Luogu/P4315/P4315.cpp

@@ -0,0 +1,199 @@
+#include <iostream>
+#include <string>
+#include <vector>
+
+using std::cin;
+using std::cout;
+using std::endl;
+
+const int N = 100005;
+
+int n, u, v, w, k, a[N];
+std::string op;
+std::pair<int, int> t[N];
+std::vector<int> g[N];
+
+// Heavy Path Decomposition
+int cnt, b[N], id[N], fa[N], dep[N], siz[N], son[N], top[N];
+void dfs1(int, int);
+void dfs2(int, int);
+void modify_path(int, int, int);
+void change_path(int, int, int);
+int query_path(int, int);
+
+// Segment Tree
+void pushup(int);
+void pushdown(int);
+void build(int, int, int);
+void modify(int, int, int, int);
+void change(int, int, int, int);
+int query(int, int, int);
+
+int main() {
+    cin >> n;
+    for (int i = 1; i < n; i++) {
+        cin >> t[i].first >> t[i].second >> a[i];
+        g[t[i].first].push_back(t[i].second);
+        g[t[i].second].push_back(t[i].first);
+    }
+    dfs1(1, 1);
+    dfs2(1, 1);
+    build(1, 1, n);
+    for (int i = 1; i < n; i++) {
+        if (dep[t[i].first] < dep[t[i].second]) std::swap(t[i].first, t[i].second);
+        modify(1, id[t[i].first], id[t[i].first], a[i]);
+    }
+    while (cin >> op, op != "Stop") {
+        if (op == "Change") {
+            cin >> k >> w;
+            change(1, id[t[k].first], id[t[k].first], w);
+        } else if (op == "Cover") {
+            cin >> u >> v >> w;
+            change_path(u, v, w);
+        } else if (op == "Add") {
+            cin >> u >> v >> w;
+            modify_path(u, v, w);
+        } else {
+            cin >> u >> v;
+            cout << query_path(u, v) << endl;
+        }
+    }
+    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;
+    top[u] = t;
+    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);
+    }
+}
+
+void modify_path(int u, int v, int d) {
+    while (top[u] != top[v]) {
+        if (dep[top[u]] < dep[top[v]]) std::swap(u, v);
+        modify(1, id[top[u]], id[u], d);
+        u = fa[top[u]];
+    }
+    if (dep[u] < dep[v]) std::swap(u, v);
+    modify(1, id[son[v]], id[u], d);
+}
+
+void change_path(int u, int v, int d) {
+    while (top[u] != top[v]) {
+        if (dep[top[u]] < dep[top[v]]) std::swap(u, v);
+        change(1, id[top[u]], id[u], d);
+        u = fa[top[u]];
+    }
+    if (dep[u] < dep[v]) std::swap(u, v);
+    change(1, id[son[v]], id[u], d);
+}
+
+int query_path(int u, int v) {
+    int res = 0;
+    while (top[u] != top[v]) {
+        if (dep[top[u]] < dep[top[v]]) std::swap(u, v);
+        res = std::max(res, query(1, id[top[u]], id[u]));
+        u = fa[top[u]];
+    }
+    if (dep[u] < dep[v]) std::swap(u, v);
+    res = std::max(res, query(1, id[son[v]], id[u]));
+    return res;
+}
+
+// == Segment Tree ===
+
+struct node {
+    int l, r, m, da, dc;
+
+    node()
+        : l(0), r(0), m(0), da(0), dc(-1) {}
+    node(int _l, int _r)
+        : l(_l), r(_r), m(0), da(0), dc(-1) {}
+} tr[N << 2];
+
+inline void pushup(int u) {
+    tr[u].m = std::max(tr[u << 1].m, tr[u << 1 | 1].m);
+}
+
+inline void pushdown(int u) {
+    node &root = tr[u], &left = tr[u << 1], &right = tr[u << 1 | 1];
+    if (root.dc != -1) {
+        left.m = right.m = root.dc;
+        left.da = right.da = 0;
+        left.dc = right.dc = root.dc;
+        root.dc = -1;
+    }
+    left.m += root.da;
+    left.da += root.da;
+    right.m += root.da;
+    right.da += root.da;
+    root.da = 0;
+}
+
+void build(int u, int l, int r) {
+    tr[u] = node(l, r);
+    if (l == r) {
+        tr[u].m = b[l];
+        return;
+    }
+    int mid = l + r >> 1;
+    build(u << 1, l, mid);
+    build(u << 1 | 1, mid + 1, r);
+    pushup(u);
+}
+
+void modify(int u, int l, int r, int d) {
+    if (l <= tr[u].l && tr[u].r <= r) {
+        tr[u].m += d;
+        tr[u].da += 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);
+    pushup(u);
+}
+
+void change(int u, int l, int r, int d) {
+    if (l <= tr[u].l && tr[u].r <= r) {
+        tr[u].m = d;
+        tr[u].da = 0;
+        tr[u].dc = d;
+        return;
+    }
+    int mid = tr[u].l + tr[u].r >> 1;
+    pushdown(u);
+    if (l <= mid) change(u << 1, l, r, d);
+    if (r > mid) change(u << 1 | 1, l, r, d);
+    pushup(u);
+}
+
+int query(int u, int l, int r) {
+    if (l <= tr[u].l && tr[u].r <= r) return tr[u].m;
+    pushdown(u);
+    int mid = tr[u].l + tr[u].r >> 1;
+    int res = 0;
+    if (l <= mid) res = std::max(res, query(u << 1, l, r));
+    if (r > mid) res = std::max(res, query(u << 1 | 1, l, r));
+    return res;
+}