poj3321Apple Tree

难点是如何：将树型结构转为用数组表示： 这里用深搜标记一个点开始和结束时间

#include <iostream>#include <cstdio>#include <vector>using namespace std;const int M = 100005;//vector<int>que[M];struct Node {    int value;    int next;}edge[M*2];int head[M];int apple[M];int cnt[M];struct node{    int s;    int e;}tree[M];int n, k;int index;void init() {   k = 0;   index = 1;    for(int i = 0; i < M; i++) {//        que[i].clear();        tree[i].s = 0;        tree[i].e = 0;        cnt[i] = 0;        apple[i] = 1;        head[i] = -1;    }}void add1(int a, int b) {    edge[index].value = b;    edge[index].next = head[a];    head[a] = index++;}void dfs(int v) {    tree[v].s = ++k;    for(int i = head[v]; i != -1; i = edge[i].next){        int u = edge[i].value;        dfs(u);    }//    for(int i = 0; i < (int)que[v].size(); i++) {////        dfs(que[v][i]);//    }    tree[v].e = k;}int lowbit(int t) {    return t & (-t);}void add(int v, int d) {    while(v <= n) {        cnt[v] += d;        v += lowbit(v);    }}int getsum(int v) {    int s = 0;    while(v > 0) {        s += cnt[v];        v -= lowbit(v);    }    return s;}int main(){    char str[5];    int a, b, m;    int sum;    scanf("%d", &n);        init();        for(int i= 1; i < n; i++) {            scanf("%d%d", &a, &b);            add1(a, b);           // que[a].push_back(b);        }        dfs(1);//        for(int i = 1; i <= n; i++){////            printf("%d  %d\n", tree[i].s, tree[i].e);//        }        for(int i = 1; i <= n; i++) {            add(i, 1);        }      scanf("%d", &m);      for(int i = 0; i < m; i++) {            scanf("%s%d", str, &a);            if(str[0] == 'C') {                if(apple[a] == 1) {                    add(tree[a].s , -1);                    apple[a] = -1;                }else {                    add(tree[a].s, 1);                    apple[a] = 1;                }            }else {                sum = getsum(tree[a].e);                sum -= getsum(tree[a].s-1);                printf("%d\n", sum);            }      }    return 0;}