FZU 2082 过路费

树链剖分模板题

  1 #include <cstdio>
  2 #include <iostream>
  3 #include <cstring>
  4 #include <algorithm>
  5 using namespace std;
  6 #define N 50010
  7 #define ls o<<1
  8 #define rs o<<1|1
  9 #define define_m int m=(l+r)>>1
 10 #define ll long long
 11 int first[N] , k;
 12 struct Edge{
 13     int x , y , next , w;
 14 }e[N<<1];
 15 
 16 void add_edge(int x , int y , int w)
 17 {
 18     e[k].x = x , e[k].y = y , e[k].next = first[x] , e[k].w = w;
 19     first[x] = k++;
 20 }
 21 
 22 int sz[N] , dep[N] , fa[N] , son[N] , top[N] , id[N] , num;
 23 void dfs(int u , int f , int d)
 24 {
 25     fa[u] = f , sz[u] = 1 , dep[u]= d , son[u]=0;
 26     int mx = 0;
 27     for(int i=first[u] ; ~i ; i=e[i].next){
 28         int v = e[i].y;
 29         if(v == f) continue;
 30         dfs(v , u , d+1);
 31         sz[u]+=sz[v];
 32         if(sz[v]>mx) mx=sz[v] , son[u]=v;
 33     }
 34 }
 35 
 36 void dfs1(int u , int f , int head)
 37 {
 38     top[u]=head , id[u]=++num;
 39     if(son[u]) dfs1(son[u] , u , head);
 40     for(int i=first[u] ; ~i ; i=e[i].next){
 41         int v = e[i].y;
 42         if(v == f || v == son[u]) continue;
 43         dfs1(v , u , v);
 44     }
 45 }
 46 
 47 ll sum[N<<2] ;
 48 int val[N];
 49 void push_up(int o)
 50 {
 51     sum[o] = sum[ls]+sum[rs];
 52 }
 53 
 54 void build(int o , int l , int r)
 55 {
 56     if(l==r){
 57         sum[o]=(ll)val[l];
 58         return ;
 59     }
 60     define_m;
 61     build(ls , l , m);
 62     build(rs , m+1 , r);
 63     push_up(o);
 64 }
 65 
 66 void update(int o , int l , int r , int p , int v)
 67 {
 68     if(l==r){
 69         sum[o]=(ll)v;
 70         return;
 71     }
 72     define_m;
 73     if(m>=p) update(ls , l , m , p , v);
 74     else update(rs , m+1 , r , p , v);
 75     push_up(o);
 76 }
 77 
 78 ll qSum(int o , int l , int r , int s , int t)
 79 {
 80     if(l>=s && r<=t) return sum[o];
 81     define_m;
 82     ll res = 0;
 83     if(m>=s) res+=qSum(ls , l , m , s , t);
 84     if(m<t) res+=qSum(rs , m+1 , r , s , t);
 85     return res;
 86 }
 87 
 88 ll calPath(int u , int v)
 89 {
 90     int top1 = top[u] , top2 = top[v] ;
 91     ll ret=0;
 92     while(top1!=top2){
 93         if(dep[top1]<dep[top2]){
 94             swap(top1 , top2);
 95             swap(u , v);
 96         }
 97         ret+=qSum(1 , 1 , num , id[top1] , id[u]);
 98         u = fa[top1];
 99         top1 = top[u];
100     }
101     if(u!=v){
102         if(dep[u]<dep[v]) swap(u,v);
103         ret+=qSum(1,1,num,id[son[v]],id[u]);
104     }
105     return ret;
106 }
107 
108 int main()
109 {
110   //  freopen("in.txt" , "r" , stdin);
111     int n , m , x , y , w;
112     while(scanf("%d%d" , &n , &m)!=EOF)
113     {
114         memset(first , -1 , sizeof(first));
115         k = 0;
116         for(int i=0 ; i<n-1 ; i++){
117             scanf("%d%d%d" , &x , &y , &w);
118             add_edge(x , y , w);
119             add_edge(y , x , w);
120         }
121         dfs(1 , 0 , 1);
122         num = 0;
123         dfs1(1 , 0 , 1);
124         for(int i=0 ; i<n-1 ; i++){
125             x = e[i*2].x , y = e[i*2].y;
126             if(fa[x]!=y) val[id[y]] = e[i*2].w;
127             else val[id[x]] = e[i*2].w;
128         }
129         build(1 , 1 , num);
130         while(m--){
131             scanf("%d%d%d" , &w , &x , &y);
132             if(w){
133                 printf("%I64d\n" , calPath(x , y));
134             }else{
135                 x--;
136                 int pos;
137                 if(fa[e[x*2].x]!=e[x*2].y) pos = id[e[x*2].y];
138                 else pos = id[e[x*2].x];
139                 update(1 , 1 , num , pos , y);
140             }
141         }
142     }
143     return 0;
144 }

 

 posted on 2015-08-27 17:30  Love风吟  阅读(188)  评论(0)  编辑  收藏  举报