hahaha

Posted 2021-01-15 thx666

#include<cstdio>
#include<cstring>
#include<cctype>
#include<cstdlib>
#include<cmath>
#include<string>
#include<iostream>
#include<algorithm>
#include<set>
#include<map>
#include<queue>
#include<stack>
#include<vector>
#define enter puts("")
using namespace std;
typedef long long ll;
const int maxn = 5e4 + 5;
int head[maxn], tot, cnt, n, m, fa[maxn];//cnt表示节点个数 ，fa[]用于查找树根 
struct E
{
    int to, next, val;
}ed[maxn];//存储输入的关系图 
struct dfsid
{
    int lef, rig;
}bc[maxn];//存储dfs序，bc[i].lef表示i第一次出现的序号， bc[i].rig表示i第二次出现的序号 
struct Tree
{
    int data, upd;
}lj[maxn << 2];//存储线段树，data表示节点值，upd表示区间更新的lazy标记 
int read()
{
    int ans = 0, op = 1;
    char ch = getchar();
    while(ch < ‘0‘ || ch > ‘9‘)
    {
        if(ch == ‘-‘) op = 0;
        ch = getchar();
    }
    while(ch >= ‘0‘ && ch <= ‘9‘)
    {
        ans *= 10;
        ans += ch - ‘0‘;
        ch = getchar();
    }
    return op ? ans : -ans;
}
void write(int x)
{
    if(x < 0)
    {
        x = -x;
        putchar(‘-‘);
    }
    if(x >= 10) write(x / 10);
    putchar(‘0‘ + x % 10);
}
void init()
{
    memset(head, -1, sizeof(head));
    memset(fa, -1, sizeof(fa));
    memset(lj, -1, sizeof(Tree) * (maxn << 2));
    tot = 0, cnt = 0;
}
void addedge(int u, int v, int w)
{
    ed[tot].to = v;
    ed[tot].next = head[u];
    ed[tot].val = w;
    head[u] = tot++;
}
void dfs(int u)
{
    cnt++;
    bc[u].lef = cnt;
    for(int i = head[u];i ^ -1;i = ed[i].next) dfs(ed[i].to);
    bc[u].rig = cnt;
}
void build(int l, int r, int now)
{
    lj[now].upd = -1;
    if(l == r) return (void)(lj[now].data = -1);
    int mid = (l + r) >> 1;
    build(l, mid, now << 1);
    build(mid + 1, r, now << 1 | 1);
}
void mark_change(int l, int r, int now, int xg)
{
    lj[now].data = xg;
    lj[now].upd = xg;
}
void pushdown(int l, int r, int now)
{
    if(lj[now].upd == -1) return ;
    int mid = (l + r) >> 1;
    mark_change(l, mid, now << 1, lj[now].upd);
    mark_change(mid + 1, r, now << 1 | 1, lj[now].upd);
    lj[now].upd = -1;
}
void update(int l, int r, int now, int ql, int qr, int xg)
{
    if(ql <= l && qr >= r) return mark_change(l, r, now, xg);
    int mid = (l + r) >> 1;
    pushdown(l, r, now);
    if(ql <= mid) update(l, mid, now << 1, ql, qr, xg);
    if(qr > mid) update(mid + 1, r, now << 1 | 1, ql, qr, xg);
}
int ask(int l, int r, int now, int id)
{
    if(l == r) return lj[now].data;
    int mid = (l + r) >> 1;
    if(id <= mid) return ask(l, mid, now << 1, id);
    else return ask(mid + 1, r, now << 1 | 1, id);
}
int main()
{
    int T;
    T = read();
    for(int t = 1; t <= T; t++)
    {
        printf("Case #%d:
", t);
        init();
        n = read();
        for(int i = 2; i <= n; i++)
        {
            int u, v;
            u = read(), v = read();
            addedge(v, u, 1);
            fa[u]++;
        }
        for(int i = 1; i <= n; i++)
        {
            //从原树根深搜
            if(fa[i] == 0)
            {
                dfs(i);
                break;
            }
        }
        build(1, cnt, 1);
        m = read();
        while(m--)
        {
            char ch[3];
            scanf("%s", ch);
            if(ch[0] == ‘C‘)
            {
                int x;
                x = read();
                write(ask(1, cnt, 1, bc[x].lef));
                enter;
            }
            else
            {
                int x, y;
                x = read(), y = read();
                update(1, cnt, 1, bc[x].lef, bc[x].rig, y);
            }
        }
    }
    return 0;
}