男神的补习
题目链接：http://acm.xidian.edu.cn/problem.php?id=1162
DFS序维护线段树
直接拿之前百度之星那题（http://www.cnblogs.com/barrier/p/5831927.html）改一下就过了
代码如下：
1 #include<cstdio> 2 #include<vector> 3 #define LL long long 4 #define N 100100 5 #define lson (x<<1) 6 #define rson (x<<1|1) 7 #define mid ((l+r)>>1) 8 using namespace std; 9 struct node{ 10 int sum,lazy; 11 }a[N<<2]; 12 int val[N],fa[N],hx[N],L[N],R[N]; 13 int idx,n,m,k,root=1,x,y,times,t; 14 bool vis[N]; 15 vector<int>e[N]; 16 void dfs(int num){ 17 vis[num]=1; 18 L[num]=++idx; 19 for(LL i=0;i<e[num].size();i++) 20 if(!vis[e[num][i]])dfs(e[num][i]); 21 hx[L[num]]=num; 22 R[num]=idx; 23 } 24 void push_up(int x){ 25 a[x].sum=min(a[lson].sum,a[rson].sum); 26 } 27 void push_down(int x){ 28 a[lson].sum+=a[x].lazy,a[lson].lazy+=a[x].lazy; 29 a[rson].sum+=a[x].lazy,a[rson].lazy+=a[x].lazy; 30 a[x].lazy=0; 31 } 32 void build(int x,int l,int r){ 33 if(l==r){ 34 a[x].sum=val[hx[l]]; 35 return; 36 } 37 build(lson,l,mid); 38 build(rson,mid+1,r); 39 push_up(x); 40 } 41 void init(){ 42 scanf("%d%d%d",&n,&m,&k); 43 for(int i=1;i<n;++i){ 44 scanf("%d%d",&x,&y); 45 e[x].push_back(y);fa[y]=x; 46 } 47 while(fa[root]!=0)root=fa[root]; 48 for(int i=1;i<=n;++i)scanf("%d",&val[i]); 49 dfs(root); 50 build(1,1,n); 51 } 52 void add(int x,int l,int r,int cl,int cr,LL v){ 53 if(cl<=l&&r<=cr){ 54 a[x].sum+=v,a[x].lazy+=v; 55 return; 56 } 57 if(a[x].lazy!=0)push_down(x); 58 if(cl<=mid)add(lson,l,mid,cl,cr,v); 59 if(mid<cr)add(rson,mid+1,r,cl,cr,v); 60 push_up(x); 61 } 62 LL query(int x,int l,int r,int ql,int qr){ 63 if(ql<=l&&r<=qr)return a[x].sum; 64 if(a[x].lazy!=0)push_down(x); 65 LL temp=1000000000; 66 if(ql<=mid)temp=min(temp,query(lson,l,mid,ql,qr)); 67 if(mid<qr)temp=min(temp,query(rson,mid+1,r,ql,qr)); 68 return temp; 69 } 70 int main(void){ 71 init(); 72 for(;query(1,1,n,L[root],R[root])<60&×<m;){ 73 scanf("%d",&t); 74 add(1,1,n,L[t],R[t],k); 75 ++times; 76 } 77 if(query(1,1,n,L[root],R[root])>=60)printf("%d ",times); 78 else printf("mdzz "); 79 }