【luogu P1903 [国家集训队]数颜色】 题解

题目链接：https://www.luogu.org/problemnew/show/P1903

裸的。。。带修莫队。。。

比较麻烦吧（对我来说是的）

两个变量分开记录查询和修改操作。

 #include <iostream>
 #include <cstdio>
 #include <algorithm>
 #include <cmath>
 #define ri register
 using namespace std;
 const int maxn = ;
 int n, m, bl, answer = , qnum = , unum = , curR, curL, now;
 int ans[maxn],a[maxn],cnt[maxn];
 struct query{
     int l, r, p, t;
     bool operator < (const query &x) const {
     if(l / bl != x.l / bl) return l / bl < x.l / bl;
     if(r / bl != x.r / bl) return r / bl < x.r / bl;
     return t < x.t;
   }
 }q[maxn];
 struct update{
     int pos, val;
 }u[maxn];
 inline void add(int pos) {
   if(++ cnt[pos] == ) answer ++;
 }
 inline void remove(int pos) {
   if(-- cnt[pos] == ) answer --;
 }
 inline void change(int now, int i) {
   if(q[i].l <= u[now].pos && u[now].pos <= q[i].r) {
     if( --cnt[a[u[now].pos]] ==  ) answer--;
     if( ++cnt[u[now].val] == )      answer++;
   }
   swap(a[u[now].pos], u[now].val);
 }
 int main()
 {
     scanf("%d%d",&n,&m);
     bl = pow(n,1.0/);
     for(ri int i = ; i <= n; i++)
     scanf("%d",&a[i]);
     for(ri int i = ; i <= m; i++)
     {
     int ch, x, y;
     while((ch = getchar()) != 'Q' && ch != 'R');
     scanf("%d%d", &x, &y);
     if(ch == 'Q') {
       q[++ qnum].l = x;
       q[qnum].r = y;
       q[qnum].t = unum;
       q[qnum].p = qnum;
     } else {
       u[++unum].pos = x;
       u[unum].val = y;
     }
   }
     sort(q+,q+qnum+);
     curL = q[].l, curR = curL - , now = ;
   for(ri int i = ; i <= qnum; i ++) {
     while(curL < q[i].l) remove(a[curL ++]);
     while(curL > q[i].l) add(a[-- curL]);
     while(curR < q[i].r) add(a[++ curR]);
     while(curR > q[i].r) remove(a[curR --]);
     while(now < q[i].t) change(++ now, i);
     while(now > q[i].t) change(now --, i);
     ans[q[i].p] = answer;
   }
     for(ri int i = ; i <= qnum; i++)
         printf("%d\n",ans[i]);
     return ;
 }