[HDOJ3974]Assign the task（建树胡搞）

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=3974

出现在窝bin的线段树专题里…第一时间想的是记录入度找出根节点，然后标记深度转换到线段树中。但是发现并不会这个姿势…于是直接深搜更新了…发现没有退化成链的数据。于是水水地过去了………………

#include <algorithm>
#include <iostream>
#include <iomanip>
#include <cstring>
#include <climits>
#include <complex>
#include <fstream>
#include <cassert>
#include <cstdio>
#include <bitset>
#include <vector>
#include <deque>
#include <queue>
#include <stack>
#include <ctime>
#include <set>
#include <map>
#include <cmath>

using namespace std;

#define fr first
#define sc second
#define pb(a) push_back(a)
#define Rint(a) scanf("%d", &a)
#define Rll(a) scanf("%I64d", &a)
#define Rs(a) scanf("%s", a)
#define FRead() freopen("in", "r", stdin)
#define FWrite() freopen("out", "w", stdout)
#define Rep(i, len) for(int i = 0; i < (len); i++)
#define For(i, a, len) for(int i = (a); i < (len); i++)
#define Cls(a) memset((a), 0, sizeof(a))
#define Clr(a, x) memset((a), (x), sizeof(a))
#define Full(a) memset((a), 0x7f7f, sizeof(a))

#define lrt rt << 1
#define rrt rt << 1 | 1
const int maxn = 50010;
int n, m;
int in[maxn];
int depth[maxn];
bool vis[maxn];
vector<int> G[maxn];
int q[maxn], front, tail;
int task[maxn];

void bfs(int rt) {
front = tail = 0;
int lv = 0;
depth[rt] = lv++; q[tail++] = rt; vis[rt] = 1;
while(front < tail) {
int u = q[front++];
Rep(i, G[u].size()) {
if(!vis[G[u][i]]) {
vis[G[u][i]] = 1;
depth[G[u][i]] = lv;
q[tail++] = G[u][i];
}
}
lv++;
}
}

void update(int rt, int p) {
task[rt] = p;
Rep(i, G[rt].size()) {
update(G[rt][i], p);
}
}

int main() {
// FRead();
int T, _ = 1;
Rint(T);
int u, v;
char cmd[6];
while(T--) {
Rint(n);
Rep(i, n+2) G[i].clear();
Cls(depth); Cls(vis); Cls(in); Clr(task, -1);
Rep(i, n-1) {
Rint(u); Rint(v);
G[v].push_back(u); in[u]++;
}
int rt = -1;
For(i, 1, n+1) if(!in[i]) rt = i;
bfs(rt);
Rint(m);
printf("Case #%d:\n", _++);
while(m--) {
Rs(cmd);
if(cmd[0] == 'C') {
Rint(u);
printf("%d\n", task[u]);
}
if(cmd[0] == 'T') {
Rint(u); Rint(v);
update(u, v);
}
}
}
return 0;
}