P3384 【模板】轻重链剖分/树链剖分

https://www.luogu.com.cn/record/92005288

Luogu/P3384/P3384.cpp

@@ -1,79 +1,26 @@
 #include <iostream>
+#include <algorithm>
 #include <vector>
 
 using std::cin;
 using std::cout;
-using std::endl;
+const char endl = '\n';
 
-const int N = 100005;
+const int N = 1e5 + 5;
 
-int p, a[N];
+int n, m, r, p, a[N];
 std::vector<int> g[N];
-
-// Segment Tree
-void build(int, int, int);
-
-// Heavy Path Decomposition
 int cnt, id[N], rid[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 modify_tree(int, int);
-long long query_path(int, int);
-long long query_tree(int);
-
-int main() {
-    int n, m, r;
-    cin >> n >> m >> r >> p;
-    for (int i = 1; i <= n; i++) {
-        cin >> a[i];
-    }
-    for (int i = 1; i < n; i++) {
-        int x, y;
-        cin >> x >> y;
-        g[x].push_back(y);
-        g[y].push_back(x);
-    }
-    dfs1(r, r);
-    dfs2(r, r);
-    build(1, 1, n);
-    while (m--) {
-        int op, x, y, z;
-        cin >> op;
-        if (op == 1) {
-            cin >> x >> y >> z;
-            modify_path(x, y, z);
-        } else if (op == 2) {
-            cin >> x >> y;
-            cout << query_path(x, y) << endl;
-        } else if (op == 3) {
-            cin >> x >> z;
-            modify_tree(x, z);
-        } else {
-            cin >> x;
-            cout << query_tree(x) << endl;
-        }
-    }
-    return 0;
-}
-
-// === Segment Tree ===
 
 struct node {
     int l, r;
     long long s, d;
 
     node()
-        : l(0),
+        : l(0), r(0), s(0), d(0) {}
-          r(0),
-          s(0),
-          d(0) {}
 
     node(int _l, int _r)
-        : l(_l),
+        : l(_l), r(_r), s(0), d(0) {}
-          r(_r),
-          s(0),
-          d(0) {}
 } tr[N << 2];
 
 inline void pushup(int u) {
@@ -82,22 +29,29 @@ inline void pushup(int u) {
 
 inline void pushdown(int u) {
     node &root = tr[u], &left = tr[u << 1], &right = tr[u << 1 | 1];
+
     left.s = (left.s + (left.r - left.l + 1) * root.d) % p;
     left.d = (left.d + root.d) % p;
+
     right.s = (right.s + (right.r - right.l + 1) * root.d) % p;
     right.d = (right.d + root.d) % p;
+
     root.d = 0;
 }
 
 void build(int u, int l, int r) {
     tr[u] = node(l, r);
+
     if (l == r) {
         tr[u].s = a[rid[l]] % p;
         return;
     }
+
     int mid = l + r >> 1;
+
     build(u << 1, l, mid);
     build(u << 1 | 1, mid + 1, r);
+
     pushup(u);
 }
 
@@ -107,29 +61,35 @@ void modify(int u, int l, int r, int d) {
         tr[u].d = (tr[u].d + d) % p;
         return;
     }
+
     pushdown(u);
+
     int mid = tr[u].l + tr[u].r >> 1;
+
     if (l <= mid) modify(u << 1, l, r, d);
     if (r > mid) modify(u << 1 | 1, l, r, d);
+
     pushup(u);
 }
 
 long long query(int u, int l, int r) {
     if (l <= tr[u].l && tr[u].r <= r) return tr[u].s % p;
     pushdown(u);
+
     int mid = tr[u].l + tr[u].r >> 1;
     long long res = 0;
+
     if (l <= mid) res = (res + query(u << 1, l, r)) % p;
     if (r > mid) res = (res + query(u << 1 | 1, l, r)) % p;
+
     return res;
 }
 
-// == 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);
@@ -139,44 +99,106 @@ void dfs1(int u, int f) {
 }
 
 void dfs2(int u, int t) {
-    id[u] = ++cnt;
+    rid[id[u] = ++cnt] = u;
-    rid[id[u]] = u;
     top[u] = t;
+
     if (!son[u]) return;
+
     dfs2(son[u], t);
+
     for (int v : g[u]) {
-        if (v == fa[u]) continue;
+        if (v == fa[u] || v == son[u]) continue;
-        if (v == son[u]) continue;
+
         dfs2(v, v);
     }
 }
 
-void modify_path(int u, int v, int d) {
+void modify_path(int u, int v, int x) {
     while (top[u] != top[v]) {
         if (dep[top[u]] < dep[top[v]]) std::swap(u, v);
-        modify(1, id[top[u]], id[u], d);
+        modify(1, id[top[u]], id[u], x);
         u = fa[top[u]];
     }
+
     if (dep[u] < dep[v]) std::swap(u, v);
-    modify(1, id[v], id[u], d);
+    modify(1, id[v], id[u], x);
 }
 
-long long query_path(int u, int v) {
+int query_path(int u, int v) {
-    long long sum = 0;
+    int res = 0;
+
     while (top[u] != top[v]) {
         if (dep[top[u]] < dep[top[v]]) std::swap(u, v);
-        sum = (sum + query(1, id[top[u]], id[u])) % p;
+        res = (res + query(1, id[top[u]], id[u])) % p;
         u = fa[top[u]];
     }
+
     if (dep[u] < dep[v]) std::swap(u, v);
-    sum = (sum + query(1, id[v], id[u])) % p;
+    res = (res + query(1, id[v], id[u])) % p;
-    return sum;
+
+    return res;
 }
 
-inline void modify_tree(int u, int d) {
+void modify_tree(int u, int x) {
-    modify(1, id[u], id[u] + siz[u] - 1, d);
+    modify(1, id[u], id[u] + siz[u] - 1, x);
 }
 
-inline long long query_tree(int u) {
+int query_tree(int u) {
     return query(1, id[u], id[u] + siz[u] - 1);
 }
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m >> r >> p;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+    }
+
+    for (int i = 1, x, y; i < n; i++) {
+        cin >> x >> y;
+
+        g[x].emplace_back(y);
+        g[y].emplace_back(x);
+    }
+
+    dfs1(r, r);
+    dfs2(r, r);
+    build(1, 1, n);
+
+    for (int i = 1; i <= m; i++) {
+        int op;
+
+        cin >> op;
+
+        if (op == 1) {
+            int x, y, z;
+
+            cin >> x >> y >> z;
+
+            modify_path(x, y, z);
+        } else if (op == 2) {
+            int x, y;
+
+            cin >> x >> y;
+
+            cout << query_path(x, y) << endl;
+        } else if (op == 3) {
+            int x, z;
+
+            cin >> x >> z;
+
+            modify_tree(x, z);
+        } else {  // op == 4
+            int x;
+
+            cin >> x;
+
+            cout << query_tree(x) << endl;
+        }
+    }
+
+    return 0;
+}