HDU 3966 Aragorn's Story (树链点权剖分，成段修改单点查询)

  1 //树链剖分 边权修改 单点查询
  2 #include <iostream>
  3 #include <cstring>
  4 #include <algorithm>
  5 #include <cstdio>
  6 using namespace std;
  7 const int MAXN = 5e4 + 10;
  8 struct data {
  9     int to , next;
 10 }edge[MAXN << 1];
 11 int head[MAXN] , cnt , tot;
 12 int top[MAXN] , par[MAXN] , son[MAXN] , size[MAXN] , dep[MAXN];
 13 int id[MAXN] , fid[MAXN]; //id[i]表示i对应在线段树上的位置 fid[i]表示线段树位置是i的叶子 对应的节点 
 14 int a[MAXN];
 15 
 16 void init() {
 17     tot = cnt = 0;
 18     memset(head , -1 , sizeof(head));
 19 }
 20 
 21 inline void add(int u , int v) {
 22     edge[tot].next = head[u];
 23     edge[tot].to = v;
 24     head[u] = tot++;
 25 }
 26 
 27 void dfs1(int u , int p , int d) {
 28     dep[u] = d , size[u] = 1 , son[u] = u , par[u] = p;
 29     for(int i = head[u] ; ~i ; i = edge[i].next) {
 30         int v = edge[i].to;
 31         if(v == p)
 32             continue;
 33         dfs1(v , u , d + 1);
 34         if(size[v] >= size[son[u]] || son[u] == u)
 35             son[u] = v;
 36         size[u] += size[v];
 37     }
 38 }
 39 
 40 void dfs2(int u , int p , int t) {
 41     top[u] = t , id[u] = ++cnt;
 42     fid[cnt] = u;
 43     if(son[u] != u)
 44         dfs2(son[u] , u , t);
 45     for(int i = head[u] ; ~i ; i = edge[i].next) {
 46         int v = edge[i].to;
 47         if(v == p || v == son[u])
 48             continue;
 49         dfs2(v , u , v);
 50     }
 51 }
 52 
 53 struct segtree {
 54     int l , r;
 55     int sum;
 56 }T[MAXN << 2];
 57 
 58 void pushup(int p) {
 59     if(T[p].sum != 0) {
 60         int ls = p << 1 , rs = (p << 1)|1;
 61         T[ls].sum += T[p].sum;
 62         T[rs].sum += T[p].sum;
 63         T[p].sum = 0;
 64     }
 65 }
 66 
 67 void build(int p , int l , int r) {
 68     int mid = (l + r) >> 1;
 69     T[p].l = l , T[p].r = r;
 70     T[p].sum = 0;
 71     if(l == r) {
 72         T[p].sum = a[fid[l]]; //
 73         return ;
 74     }
 75     build(p << 1 , l , mid);
 76     build((p << 1)|1 , mid + 1 , r);
 77 }
 78 
 79 void updata(int p , int l , int r , int num) {
 80     int mid = (T[p].l + T[p].r) >> 1;
 81     if(T[p].l == l && T[p].r == r) {
 82         T[p].sum += num;
 83         return ;
 84     }
 85     pushup(p);
 86     if(r <= mid) {
 87         updata(p << 1 , l , r , num);
 88     }
 89     else if(l > mid) {
 90         updata((p << 1)|1 , l , r , num);
 91     }
 92     else {
 93         updata(p << 1 , l , mid , num);
 94         updata((p << 1)|1 , mid + 1 , r , num);
 95     }
 96 }
 97 
 98 int query(int p , int pos) {
 99     int mid = (T[p].l + T[p].r) >> 1;
100     if(T[p].l == T[p].r && T[p].r == pos) {
101         return T[p].sum;
102     }
103     pushup(p);
104     if(pos <= mid) {
105         return query(p << 1 , pos);
106     }
107     else {
108         return query((p << 1)|1 , pos);
109     }
110 }
111 
112 void change(int u , int v , int num) {
113     int fu = top[u] , fv = top[v];
114     int sum = 0;
115     while(fu != fv) {
116         if(dep[fu] > dep[fv]) {
117             updata(1 , id[fu] , id[u] , num);
118             u = par[fu];
119             fu = top[u];
120         }
121         else {
122             updata(1 , id[fv] , id[v] , num);
123             v = par[fv];
124             fv = top[v];
125         }
126     }
127     if(dep[u] >= dep[v]) {
128         updata(1 , id[v] , id[u] , num);
129     }
130     else {
131         updata(1 , id[u] , id[v] , num);
132     }
133 }
134 
135 int main()
136 {
137     int n , u , v , m , xx;
138     while(~scanf("%d %d %d" , &n , &xx , &m)) {
139         init();
140         for(int i = 1 ; i <= n ; ++i) {
141             scanf("%d" , a + i);
142         }
143         for(int i = 1 ; i < n ; ++i) {
144             scanf("%d %d" , &u , &v);
145             add(u , v);
146             add(v , u);
147         }
148         cnt = 0;
149         dfs1(1 , 1 , 0);
150         dfs2(1 , 1 , 1);
151         build(1 , 1 , cnt);
152         char q[10];
153         while(m--) {
154             scanf("%s" , q);
155             if(q[0] == ‘Q‘) {
156                 scanf("%d" , &xx);
157                 printf("%d\n" , query(1 , id[xx]));
158             }
159             else if(q[0] == ‘I‘) {
160                 scanf("%d %d %d" , &u , &v , &xx);
161                 change(u , v , xx);
162             }
163             else {
164                 scanf("%d %d %d" , &u , &v , &xx);
165                 change(u , v , -xx);
166             }
167         }
168     }
169     return 0;
170 }