单点修改树中某个节点,查询子树的性质.DFS序 子树序列一定在父节点的DFS序列之内,所以可以用线段树维护.
1: /*
2: DFS序 +线段树
3: */
4:
5: #include <cstdio>
6: #include <cstring>
7: #include <cctype>
8: #include <algorithm>
9: #include <vector>
10: #include <iostream>
11: using namespace std;
12:
13: #define LL(a) a<<1
14: #define RR(a) a<<1|1
15:
16: const int MaxL = 200002;
17:
18: int pre[MaxL]; // first travel
19: int nxt[MaxL]; // nxt travel
20: bool vis[MaxL];
21: int N;
22: vector<vector<int> > E(MaxL);
23:
24: struct Seg_tree
25: {
26: int left, right;
27: int sum;
28: } tt[MaxL<<2];
29:
30:
31: void PushUp(int idx)
32: {
33: tt[idx].sum = tt[LL(idx)].sum + tt[RR(idx)].sum;
34: }
35:
36: void build(int l,int r,int idx)
37: {
38: tt[idx].left = l, tt[idx].right = r;
39: tt[idx].sum = r-l+1;
40: if (l == r) return ;
41: int m = (l + r) >> 1;
42: build(l,m, LL(idx));
43: build(m+1, r, RR(idx));
44: }
45:
46: void update(int p, int idx = 1)
47: {
48: if(p == tt[idx].left && p == tt[idx].right)
49: {
50: tt[idx].sum ^=1;
51: return ;
52: }
53: int mid = (tt[idx].left + tt[idx].right)>>1;
54: if(p <= mid) update(p, LL(idx));
55: else update(p, RR(idx));
56: PushUp(idx);
57: }
58:
59: int query(int l, int r, int idx = 1)
60: {
61: if(l == tt[idx].left && r ==tt[idx].right)
62: return tt[idx].sum;
63: int mid = (tt[idx].left + tt[idx].right)>>1;
64: if(r <= mid) return query(l,r, LL(idx));
65: else if(l> mid) return query(l,r, RR(idx));
66: else
67: return query(l, mid, LL(idx))+ query(mid+1, r, RR(idx));
68: }
69:
70: int mark = 1;
71: void dfs( int a)
72: {
73: vis[a] = 1;
74: pre[a] = mark++;
75: for(int i=0; i<E[a].size(); i++)
76: {
77: if(!vis[E[a][i]])
78: dfs(E[a][i]);
79: }
80: nxt[a] = mark++;
81: }
82: int main()
83: {
84: // freopen("1.txt","r",stdin);
85: memset(pre, 0, sizeof(pre));
86: memset(nxt, 0 ,sizeof(nxt));
87: memset(vis, 0 ,sizeof(vis));
88:
89: scanf("%d", &N);
90: for(int i=1; i<N; i++)
91: {
92: int a,b;
93: scanf("%d%d", &a,&b);
94: E[a].push_back(b);
95: E[b].push_back(a);
96: }
97: dfs(1);
98:
99: N*=2;
100: build(1, N, 1);
101: int M;
102: scanf("%d", &M);
103: for(int i=1; i<=M; i++)
104: {
105: char c;
106: int a;
107: scanf("%s", &c);
108: scanf("%d",&a);
109: if(c =='Q')
110: {
111: cout<<query(pre[a],nxt[a], 1) /2<<endl;
112: }
113: else
114: {
115: update(pre[a],1);
116: update(nxt[a],1);
117: }
118: }
119: return 0;
120: }
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