poj3321_Apple Tree（树状数组）

#include<iostream>
#include<vector>
#include<string.h>
#include<cstdio>
using namespace std;

struct node{
int p;
node* nex;
};
node edge[100010];
int lran[100010], rran[100010], bit[100010];
bool hava[100010];
int n, key;

int lowbit(int i)
{
return i&(-i);
}

void update(int i, int x)
{
while (i <= n)
{
bit[i] += x;
i += lowbit(i);
}
}

int query(int i)
{
int sum = 0;
while (i > 0)
{
sum += bit[i];
i -= lowbit(i);
}
return sum;
}

void dfs(int i)
{
lran[i] = key;
node *t = edge[i].nex;
while (t)
{
key++;
dfs(t->p);
t = t->nex;
}
rran[i] = key;
}

int main()
{
while (scanf("%d", &n)!=-1){
for (int i = 0; i <= n; i++)
edge[i].nex = 0;
for (int i = 0; i < n - 1; i++)
{
int a, b;
scanf("%d %d", &a, &b);
node *t = new node;
t->p = b;
t->nex = 0;
if (edge[a].nex == 0)
edge[a].nex = t;
else{
node *p = edge[a].nex;
node *pp = 0;
while (p)
{
pp = p;
p = p->nex;
}
pp->nex = t;
}
}
memset(hava, true, sizeof(hava));
for (int i = 1; i <= n; i++)
update(i, 1);
key = 1;
dfs(1);
int m;
scanf("%d", &m);
for (int i = 0; i < m; i++)
{
getchar();
char c; int a;
scanf("%c %d", &c, &a);
if (c == 'Q')
printf("%d\n", query(rran[a]) - query(lran[a]) + (hava[lran[a]] ? 1 : 0));
else
{
if (hava[lran[a]])
update(lran[a], -1);
else
update(lran[a], 1);
hava[lran[a]] = !hava[lran[a]];
}
}
}
return 0;
}