BZOJ3631 松鼠的新家(树链剖分)

题目链接 松鼠的新家

差不多可以说是树链剖分的模板题了，直接维护即可。

 #include <bits/stdc++.h>

 using namespace std;

 #define REP(i,n)                for(int i(0); i <  (n); ++i)
 #define rep(i,a,b)              for(int i(a); i <= (b); ++i)
 #define dec(i,a,b)              for(int i(a); i >= (b); --i)
 #define for_edge(i,x)           for(int i = H[x]; i; i = X[i])

 #define LL      long long
 #define ULL     unsigned long long
 #define MP      make_pair
 #define PB      push_back
 #define FI      first
 #define SE      second
 #define INF     1 << 30

 const int N     =          +       ;
 const int M     =           +       ;
 const int Q     =            +       ;
 const int A     =              +       ;

 int E[N << ], H[N << ], X[N << ];
 int c[N];
 int top[N];
 int fa[N];
 int deep[N];
 int num[N];
 int son[N];
 int fp[N];
 int p[N];
 int et, pos;
 int a[N];
 int n, x, y;

 inline int lowbit(int x){ return (x) & (-x);}

 inline int query(int x){int ret = ; for (; x; x -= lowbit(x)) ret += c[x]; return ret;}
 inline void add(int x, int val){ for (; x <= n; x += lowbit(x)) c[x] += val;}

 inline void addedge(int a, int b){
     E[++et] = b, X[et] = H[a], H[a] = et;
     E[++et] = a, X[et] = H[b], H[b] = et;
 }

 void dfs(int x, int pre){
     deep[x] = deep[pre] + ;
     fa[x] = pre;
     num[x] = ;
     for_edge(i, x){
         int v = E[i];
         if (v != pre){
             dfs(v, x);
             num[x] += num[v];
             if (son[x] != - || num[v] > num[son[x]])
                 son[x] = v;
         }
     }
 }

 void getpos(int x, int sp){
     top[x] = sp;
     p[x] = ++pos;
     fp[p[x]] = x;
     if (son[x] == -) return;
     getpos(son[x], sp);
     for_edge(i, x){
         int v = E[i];
         if (v != son[x] && v != fa[x])
             getpos(v, v);
     }
 }

 void cover(int u, int v, int val){
     int f1 = top[u], f2 = top[v];
     int tmp = ;
     while (f1 != f2){
         if (deep[f1] < deep[f2]){
             swap(f1, f2);
             swap(u, v);
         }
         add(p[f1], val);
         add(p[u] + , -val);
         u = fa[f1];
         f1 = top[u];
     }

     if (deep[u] > deep[v]) swap(u, v);
     add(p[u], val);
     add(p[v] + , -val);
 }

 int main(){

     scanf("%d", &n);
     rep(i, , n) scanf("%d", a + i);
     rep(i, , n - ){
         scanf("%d%d", &x, &y);
         addedge(x, y);
     }

     memset(son, -, sizeof son);
     dfs(, );
     getpos(, );
     rep(i, , n - ){
         x = a[i], y = a[i + ];
         cover(x, y, );
     }

     rep(i, , n) if (i == a[]) printf("%d\n", query(p[i]));
     else printf("%d\n", query(p[i]) - );

     return ;

 }