BZOJ 2120: 数颜色

/*
BZOJ 2120: 数颜色

正解貌似是树状数组 + 主席树？

果然莫队是个神器。。

带修改的莫队

记录每次查询的上一次修改操作

修改后更新答案再改回来

这样就仍然可以维持莫队算法的复杂度

*/
#include <algorithm>
#include <cstdlib>
#include <cstdio>
#include <cmath>

#define Max 1000005

void read (int &now)
{
now = 0;
register char word = getchar ();
while (word < '0' || word > '9')
word = getchar ();
while (word >= '0' && word <= '9')
{
now = now * 10 + word - '0';
word = getchar ();
}
}

int belong[Max];
bool visit[Max];
int L, R, Pos;

struct Query_Data
{
int l, r;

int Id;
int Last_Change;

bool operator < (const Query_Data &now) const
{
if (belong[this->l] == belong[now.l])
return this->r < now.r;
return belong[this->l] < belong[now.l];
}
};
Query_Data query[Max];

struct Change_Data
{
int pos;
int color;
int Last;
};

Change_Data change[Max];

int res[Max], count[Max];
int number[Max];
int N, M;

int Result;

inline void Updata_Change (int now, bool type)
{
if (type)
{
res[now] = number[change[now].pos];
number[change[now].pos] = change[now].color;
if (change[now].pos >= L && change[now].pos <= R)
{
count[res[now]] --;
if (!count[res[now]])
Result --;
count[change[now].color]++;
if (count[change[now].color] == 1)
Result ++;
}
}
else
{
number[change[now].pos] = res[now];
if (change[now].pos >= L && change[now].pos <= R)
{
count[change[now].color] --;
if (!count[change[now].color])
Result --;
count[res[now]] ++;
if (count[res[now]] == 1)
Result ++;
}
}
}

inline void Updata (int now, bool type)
{
if (type)
{
if (count[number[now]] == 0)
Result ++;
count[number[now]] ++;
}
else
{
if (count[number[now]] == 1)
Result --;
count[number[now]] --;
}
}

int Answer[Max];

int main (int argc, char *argv[])
{
read (N);
read (M);
int K_Size = sqrt (N);
int Query_Count = 0, Change_Count = 0;
for (int i = 1; i <= N; i ++)
{
read (number[i]);
belong[i] = (i + 1) / K_Size;
}
char type[5];
int x, y;
for (int i = 1; i <= M; i ++)
{
scanf ("%s", type);
read (x);
read (y);
if (type[0] == 'R')
{
Change_Count ++;
change[Change_Count].pos = x;
change[Change_Count].color = y;
}
else
{
Query_Count ++;
query[Query_Count].l = x;
query[Query_Count].r = y;
query[Query_Count].Id = Query_Count;
query[Query_Count].Last_Change = Change_Count;
}
}
std :: sort (query + 1, query + 1 + Query_Count);
L = 1, R = 0;
Pos = 0;
for (int i = 1; i <= Query_Count; i ++)
{
while (Pos < query[i].Last_Change)
Updata_Change (++ Pos, true);
while (Pos > query[i].Last_Change)
Updata_Change (Pos -- , false);
while (L < query[i].l)
Updata (L ++, false);
while (L > query[i].l)
Updata (-- L, true);
while (R < query[i].r)
Updata (++ R, true);
while (R > query[i].r)
Updata (R --, false);
Answer[query[i].Id] = Result;
}
for (int i = 1; i <= Query_Count; i ++)
printf ("%d\n", Answer[i]);
//system ("pause");
return 0;
}