POJ3321 Apple Tree

#include <iostream>#include <cstdio>#include <cstring>using namespace std;const int maxn = 100002;//3321Accepted4468K438MSC++1790B2013-08-12 23:20:18struct node1 {    int next, tail;}edge[maxn];struct node2 {    int r, l;}apple[maxn];int s[maxn], cnt, c[maxn], a[maxn];void dfs(int u) {    int i;    apple[u].l = cnt;    for(i = s[u]; i != -1; i = edge[i].next) {        dfs(edge[i].tail);    }    apple[u].r = ++cnt;}inline int lowbit(int x) {    return x&(-x);}void change(int x) {    int i;    if(a[x]) {        for(i = x; i <= cnt; i += lowbit(i)) {             c[i]++;        }    }    else {        for(i = x; i <= cnt; i += lowbit(i)) {            c[i]--;        }    }}int sum(int x) {    int i, res = 0;    for(i = x; i > 0; i -= lowbit(i))        res += c[i];    return res;}int main() {    int i, n, m, t1, t2, t;    char str[3];    scanf("%d", &n);    memset(s, -1, sizeof(s[0])*(n+1));    memset(c, 0, sizeof(c[0])*(n+1));    memset(apple, 0, sizeof(apple[0])*(n+1));    for(i = 0; i < n-1; i++) {        scanf("%d%d", &t1, &t2);        edge[i].tail = t2;        edge[i].next = s[t1];        s[t1] = i;    }    cnt = 1;    dfs(1);    scanf("%d", &m);    //a[1] = 1; change(a[1]); c[1] = 0;    for(i = 2; i <= n+1; i++) {        a[i] = 1;        change(i);    }    while(m--) {        scanf("%s", str);        scanf("%d", &t);        getchar();        if(str[0]=='Q') {            int res = sum(apple[t].r) - sum(apple[t].l);            printf("%d\n", res);        }        else {            a[apple[t].r] = (a[apple[t].r] + 1)%2;            change(apple[t].r);        }    }    return 0;}/**71 21 42 32 74 54 64Q 1Q 3C 3Q 1**/