POJ 2777 Count Color

#include<cstdio>
#include<cstdlib>
#include<cstring>
bool visit[35];
int ans;

struct Tree{
	int s;
	int t;
	int c;
}tree[270010];

void build(int s,int t,int id){
	tree[id].s=s;
	tree[id].t=t;
	tree[id].c=1;
	if(s!=t){
		int mid=(tree[id].s+tree[id].t)>>1;
		build(s,mid,id*2);
		build(mid+1,t,id*2+1);
	}
}

void insert(int s,int t,int id,int colour){
	if(tree[id].s==s && tree[id].t==t){
		tree[id].c=colour;
		return ;
	}
	if(colour==tree[id].c)
		return ;
	if(tree[id].c>0){
		tree[id*2].c=tree[id].c;
		tree[id*2+1].c=tree[id].c;
	}
	int mid=(tree[id].s+tree[id].t)>>1;
	if(mid<s)
		insert(s,t,id*2+1,colour);
	else if(mid>=t)
		insert(s,t,id*2,colour);
	else{
		insert(s,mid,id*2,colour);
		insert(mid+1,t,id*2+1,colour);
	}
	if(tree[id*2+1].c!=tree[id*2].c || !tree[id*2+1].c || !tree[id*2].c)
		tree[id].c=0;
}

void query(int s,int t,int id){
	if(tree[id].c!=0){
		if(!visit[tree[id].c]){
			visit[tree[id].c]=1;
			ans++;
		}
		return;
	}
	int mid=(tree[id].s+tree[id].t)>>1;
	if(mid<s)
		query(s,t,id*2+1);
	else if(mid>=t)
		query(s,t,id*2);
	else{
		query(s,mid,id*2);
		query(mid+1,t,id*2+1);
	}
}

int main(){
	int n,i,a,b,c,m,cc;
	scanf("%d %d %d",&n,&cc,&m);
	build(1,n,1);
	for(i=1;i<=m;i++){
		char ss[5];
		scanf("%s",ss);
		if(ss[0]=='C'){
			scanf("%d %d %d",&a,&b,&c);	
			if(a>b){
				int tem;
				tem=a,a=b;b=tem;
			}
			insert(a,b,1,c);
		}
		else{
			scanf("%d %d",&a,&b);	
			memset(visit,0,sizeof(visit));
			ans=0;
			if(a>b){
				int tem;
				tem=a,a=b;b=tem;
			}
			query(a,b,1);
			printf("%d\n",ans);
		}
	}
}