D 树上求和
题目地址:
基本思路:
比较裸的一道题,没有什么思维量,
首先要维护子树状态,很明显我们可以求个序,然后用数据结构去维护,
观察一下题意,要维护区间平方和,进行区间查询和区间修改,所以考虑线段树。
那么维护区间平方和的线段树怎么写函数,其实也比较简单,
假设这段区间内的平方和开始为,
那么我们将整个区间加,就变为
化简一下提出来其实就是
所以我们在维护区间平方和的同时在维护一下那部分普通的区间和,然后就很容易进行了。
参考代码:
#pragma GCC optimize(2) #pragma GCC optimize(3) #include <bits/stdc++.h> using namespace std; #define IO std::ios::sync_with_stdio(false) #define int long long #define rep(i, l, r) for (int i = l; i <= r; i++) #define per(i, l, r) for (int i = l; i >= r; i--) #define mset(s, _) memset(s, _, sizeof(s)) #define pb push_back #define pii pair <int, int> #define mp(a, b) make_pair(a, b) #define INF (int)1e18 inline int read() { int x = 0, neg = 1; char op = getchar(); while (!isdigit(op)) { if (op == '-') neg = -1; op = getchar(); } while (isdigit(op)) { x = 10 * x + op - '0'; op = getchar(); } return neg * x; } inline void print(int x) { if (x < 0) { putchar('-'); x = -x; } if (x >= 10) print(x / 10); putchar(x % 10 + '0'); } const int maxn = 1e5 + 10; const int mod = 23333; int n,q; struct edge { int next, v; }edges[maxn << 1]; int cnt,tot,w[maxn]; int head[maxn]; void init() { memset(head, -1, sizeof(head)); cnt = 0; tot = 0; } void add_edge(int u,int v) { edges[cnt].next = head[u]; edges[cnt].v = v; head[u] = cnt++; } int L[maxn],R[maxn],dfn[maxn]; void dfs(int u,int ***] = ++tot; dfn[tot] = u; for (int i = head[u]; i != -1; i = edges[i].next) { int v = edges[i].v; if (v == fa) continue; dfs(v, u); } R[u] = tot; } struct node{ int l,r,sum,res,add; }t[maxn<<2]; inline void push_up(int p) { t[p].res = (t[p << 1].res + t[p << 1 | 1].res) % mod; t[p].sum = (t[p << 1].sum + t[p << 1 | 1].sum) % mod; } inline void push_down(int p) { if (t[p].add) { int v = t[p].add; t[p].add = 0; t[p << 1].add = (t[p << 1].add + v) % mod; t[p << 1 | 1].add = (t[p << 1 | 1].add + v) % mod; int ll = t[p << 1].r - t[p << 1].l + 1; int lr = t[p << 1 | 1].r - t[p << 1 | 1].l + 1; t[p << 1].res = (t[p << 1].res + ll * v * v % mod + 2 * t[p << 1].sum * v % mod) % mod; t[p << 1 | 1].res = (t[p << 1 | 1].res + lr * v * v % mod + 2 * t[p << 1 | 1].sum * v % mod) % mod; t[p << 1].sum = (t[p << 1].sum + ll * v) % mod; t[p << 1 | 1].sum = (t[p << 1 | 1].sum + lr * v) % mod; } } void build(int p,int l,int r) { t[p].l = l; t[p].r = r; if (l == r) { t[p].sum = w[dfn[l]]; t[p].res = t[p].sum * t[p].sum % mod; return; } int mid = l + r >> 1; build(p << 1, l, mid); build(p << 1 | 1, mid + 1, r); push_up(p); } void change(int p,int l,int r,int v) { if (t[p].l == l && t[p].r == r) { t[p].res = (t[p].res + (r - l + 1) * v * v % mod + 2 * t[p].sum * v % mod) % mod; t[p].sum = (t[p].sum + (r - l + 1) * v % mod) % mod; t[p].add = (t[p].add + v) % mod; return; } push_down(p); int mid = (t[p].l + t[p].r) >> 1; if (r <= mid) change(p << 1, l, r, v); else if (l > mid) change(p << 1 | 1, l, r, v); else change(p << 1, l, mid, v), change(p << 1 | 1, mid + 1, r, v); push_up(p); } int ask(int p,int l,int r) { if (t[p].l == l && t[p].r == r) return t[p].res % mod; push_down(p); int mid = (t[p].l + t[p].r) >> 1; if (r <= mid) return ask(p << 1, l, r); else if (l > mid) return ask(p << 1 | 1, l, r); else return (ask(p << 1, l, mid) + ask(p << 1 | 1, mid + 1, r)) % mod; } signed main() { n = read(),q = read(); rep(i,1,n) w[i] = read(); init(); rep(i,1,n-1) { int u = read(), v = read(); add_edge(u, v); add_edge(v, u); } dfs(1,0); build(1,1,n); while (q--){ int op = read(); if(op == 1){ int x = read(),y = read(); change(1,L[x],R[x],y); }else{ int x = read(); int ans = ask(1,L[x],R[x]); print(ans); puts(""); } } return 0; }