Luogu P1903 BZOJ 2120 数颜色 带修改的莫队

#include<bits/stdc++.h>
typedef long long LL;
using namespace std; 
const int maxn = 50010;
int n,m,sqr,totc=0,totq=0; 
int pos[maxn]={},las[maxn]={},ans[maxn]={},cnt[1000010]={},col[maxn]={};
char ch[2];
struct C{int x,v,la;}c[maxn];
struct Q{int l,r,k,id;}q[maxn];
inline bool cmd(Q a, Q b){
	if(a.l==b.l){
		if(a.r==b.r)return a.k<b.k;
		return a.r<b.r;
	}
	return a.l<b.l;
}
int main(){
	scanf("%d%d",&n,&m);sqr=pow((double)n,2.0/3.0);
	for(int i=1;i<=n;++i){scanf("%d",&col[i]);las[i]=col[i];}
	for(int i=1;i<=n;++i)pos[i]=(i-1)/sqr+1; 
	for(int i=1;i<=m;++i){
		int x,y;scanf("%s%d%d",ch,&x,&y);
		if(ch[0]==‘Q‘){ q[++totq].l = x; q[totq].r = y; q[totq].id = totq; q[totq].k = totc; }
		else{ c[++totc].x = x; c[totc].v = y; c[totc].la = las[x]; las[x] = y; }
	}
	sort(q+1,q+totq+1,cmd);
	int tk=0,tl=1,tr=0,tnow=0;
	for(int i=1;i<=totq;++i){
		while(tk<q[i].k){
			++tk;
			if(tl<=c[tk].x&&c[tk].x<=tr){
				--cnt[c[tk].la];++cnt[c[tk].v];
				if(cnt[c[tk].la]==0)--tnow;
				if(cnt[c[tk].v]==1)++tnow;
			}
			col[c[tk].x]=c[tk].v;
		}
		while(tk>q[i].k){
			if(tl<=c[tk].x&&c[tk].x<=tr){
				++cnt[c[tk].la];--cnt[c[tk].v];
				if(cnt[c[tk].la]==1)++tnow;
				if(cnt[c[tk].v]==0)--tnow;
			}
			col[c[tk].x]=c[tk].la;
			--tk;
		}
		while(tl<q[i].l){if(cnt[col[tl]]==1)--tnow;--cnt[col[tl]];++tl;}
		while(tl>q[i].l){--tl;++cnt[col[tl]];if(cnt[col[tl]]==1)++tnow;}
		while(tr<q[i].r){++tr;++cnt[col[tr]];if(cnt[col[tr]]==1)++tnow;}
		while(tr>q[i].r){if(cnt[col[tr]]==1)--tnow;--cnt[col[tr]];--tr;}
		ans[q[i].id]=tnow;
	}
	for(int i=1;i<=totq;++i)printf("%d\n",ans[i]);
	return 0;
}