hdu5023--A Corrupt Mayor's Performance Art

来源：2014 ACM/ICPC Asia Regional Guangzhou Online

题意：长度为n的一个线段，1-30为颜色代号。初始状态每个单位长度颜色都为2，然后有q次操作，P操作把区间内的颜色全部换为别的颜色，Q操作从小到大输出区间内所有的颜色代号。

线段树区间更新（裸题），一场网络赛让我学会了区间更新。

#include <set>
#include <map>
#include <cmath>
#include <ctime>
#include <queue>
#include <stack>
#include <cctype>
#include <cstdio>
#include <string>
#include <vector>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
const int inf = 0x3f3f3f3f;
const double eps = 1e-8;
const int maxn = 1e6+10;
int n,m,seg[maxn<<2];
bool ans[35];
void push_down(int l,int r,int pos)
{
	if (~seg[pos])
	{
		seg[pos<<1] = seg[pos<<1|1] =seg[pos];
	}
	seg[pos] = -1;
}
void push_up(int l,int r,int pos)
{
	if (seg[pos<<1] == seg[pos<<1|1])
		seg[pos] = seg[pos<<1];
	else
		seg[pos] = -1;
}
void update(int l,int r,int pos,int ua,int ub,int col)
{
	if (ua <= l && ub >= r)
	{
		seg[pos] = col;
		return;
	}
	if (~seg[pos])
		push_down(l,r,pos);
	int mid = (l + r) >> 1;
	if (ua <= mid)
		update(l,mid,pos<<1,ua,ub,col);
	if (ub > mid)
		update(mid+1,r,pos<<1|1,ua,ub,col);
	push_up(l,r,pos);
}
void query(int l,int r,int pos,int ua,int ub)
{
	if (~seg[pos])
	{
		ans[seg[pos]] = 1;
		return;
	}
	int mid = (l + r) >> 1;
	if (ua <= mid)
		query(l,mid,pos<<1,ua,ub);
	if (ub > mid)
		query(mid+1,r,pos<<1|1,ua,ub);
}
int main(void)
{
    #ifndef ONLINE_JUDGE
        freopen ("in.txt","r",stdin);
    #endif
    while (scanf ("%d%d",&n,&m),n&&m)
	{
		update(1,n,1,1,n,2);
		for (int i = 0; i < m; i++)
		{
			char cmd[5];
			scanf ("%s",cmd);
			if (cmd[0] == 'P')
			{
				int x,y,z;
				scanf ("%d%d%d",&x,&y,&z);
				update(1,n,1,x,y,z);
			}
			if (cmd[0] == 'Q')
			{
				int x,y;
				scanf ("%d%d",&x,&y);
				memset(ans,0,sizeof(ans));
				query(1,n,1,x,y);
				bool first = 0;
				for (int i = 1; i <= 30; i++)
				{
					if (ans[i])
					{
						if (!first)
							printf("%d",i),first = 1;
						else
							printf(" %d",i);
					}
				}
				printf("\n");
			}
		}
	}
    return 0;
}