[luogu U8984][新创无际夏日公开赛] 冰精冻西瓜 [树状数组]

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<iostream>
 4 #include<vector>
 5 #include<cmath>
 6 using namespace std;
 7 
 8 inline int read(){
 9     int re=0;
10     char ch;
11     bool flag=0;
12     while((ch=getchar())!=‘-‘&&(ch<‘0‘||ch>‘9‘));
13     ch==‘-‘?flag=1:re=ch-‘0‘;
14     while((ch=getchar())>=‘0‘&&ch<=‘9‘)  re=(re<<1)+(re<<3)+ch-‘0‘;
15     return flag?-re:re;
16 }
17 
18 typedef long double lb;
19 
20 struct edge{
21     int to,next;
22     lb w;
23     edge(int to=0,int next=0,lb w=0):
24         to(to),next(next),w(w){}
25 };
26 
27 const int maxn=100001;
28 
29 const lb eps=1e-8;
30 vector<edge> edges;
31 vector<edge> tree;
32 int n,m,cnt,root=1;
33 int head[maxn],tmp_head[maxn];
34 lb data[maxn];
35 
36 bool oo(lb ww){
37     if(fabs(ww)<eps)  return 0;
38     return 1;
39 }
40 
41 inline void add_edge(int from,int to,lb w){
42     edges.push_back(edge(to,head[from],w));
43     head[from]=++cnt;
44     edges.push_back(edge(from,head[to],w));
45     head[to]=++cnt;
46 }
47 
48 inline void add_tree(int from,int to,lb w){
49     tree.push_back(edge(to,tmp_head[from],w));
50     tmp_head[from]=++cnt;
51 }
52 
53 void dfs_tree(int x,int fa){
54     for(int ee=head[x];ee;ee=edges[ee].next)
55         if(edges[ee].to!=fa){
56             add_tree(x,edges[ee].to,edges[ee].w);
57             dfs_tree(edges[ee].to,x);
58         }
59 }
60 
61 void dfs(int ss,lb ww){
62     data[ss]+=ww;
63     for(int ee=head[ss];ee;ee=tree[ee].next)
64         if(oo(tree[ee].w))
65             dfs(tree[ee].to,ww*tree[ee].w);
66 }
67 
68 int main(){
69     //freopen("temp.in","r",stdin);
70     cnt=0;
71     n=read();
72     edges.push_back(edge(0,0,0));
73     for(int i=1;i<n;i++){
74         int from=read(),to=read();
75         lb w;scanf("%Lf",&w);
76         add_edge(from,to,w);
77     }
78     cnt=0;
79     tree.push_back(edge(0,0,0));
80     dfs_tree(root,0);
81     swap(head,tmp_head);
82     m=read();
83     for(int i=0;i<m;i++){
84         int op=read(),ss=read();
85         if(op&8){
86             printf("%.8Lf\n",data[ss]);
87         }
88         else{
89             lb ww;scanf("%Lf",&ww);
90             dfs(ss,ww);
91         }
92     }
93     return 0;
94 }