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;
}