POJ 3321 Apple Tree

Reference Source: http://www.cnblogs.com/frog112111/p/3269281.html

/**poj 3321 Tree Array + dfs* Test instructions: An apple tree, there are N nodes, each node has or only 1 apples, at the beginning of each node has Apple * gives n-1 node relationship * M Operations: * C x if the X node has an apple, then take off, if not, will grow a A * Q X asks the sum of all the nodes below the X node for the *//*dfs of the first access time and last access time for each node, and the node between begin[x] and End[x] is the subtree of x (End[u) with a tree-like array (getsum)- Getsum (Begin[u]-1) */#include <cstdio> #define LOWBIT (x) x& (-X) #define MAXN 100010int C[MAXN], N;int first[ MAXN]; Record the head node of the adjacency table with the number int BEGIN[MAXN];  Start time of each node int END[MAXN]; End time of each node bool HAS[MAXN]; Record whether the node has an Apple int count;void update (int x, int val) {for (int i = x; i <= n; i + = Lowbit (i)) {C[i] + = val;}} int getsum (int x) {int sum = 0;for (int i = x; i > 0; I-= Lowbit (i)) {sum + = C[i];} return sum;} struct Edge {int V, next;} EDGE[MAXN]; Record edge information void insert (int u, int v) {edge[count].v = V;edge[count].next = First[u];first[u] = count++;} void Dfs (int x) {Begin[x] = + + count;for (int i = first[x]; I! =-1; i = edge[i].next) {dfs (EDGE[I].V);} END[X] = count;} int main () {int u, V, M, Ans;char s[10];scanf ("%d", &n), Count = 0;for (int i = 0; I <= MAXN; i++) {First[i] =-1;} for (int i = 0; i < n-1; i + +) {scanf ("%d%d", &u, &v); Insert (U, v);}  Count = 0;dfs (1);//for (int i = 0; i < n; i++) {//printf ("%d%d%d%d%d\n", First[i], begin[i], end[i], EDGE[I].V, Edge[i].next);//}for (int i = 1; I <= n; i++) {Update (I, 1); has[i] = true;} scanf ("%d", &m), while (m--) {scanf ("%s%d", S, &u), if (s[0] = = ' Q ') {printf ("%d\n", Getsum (End[u])-Getsum (begin[ U]-1));} else {if (Has[u]) {update (Begin[u],-1);} else {update (begin[u], 1);} Has[u] =!has[u];}} return 0;}

　　

POJ 3321 Apple Tree