hdu 4046 Panda

Panda

#include"stdio.h"
#include"string.h"
#define N 50005
#define lowbit(i) (i&(-i))
char str
;
int c
,n;
int judge(char c1,char c2,char c3)
{
if(c1=='w'&&c2=='b'&&c3=='w')
return 1;
return 0;
}
void modify(int x,int d)
{
int i;
for(i=x;i<n;i+=lowbit(i))
c[i]+=d;
}
int getsum(int x)
{
int i,s=0;
for(i=x;i>0;i-=lowbit(i))
s+=c[i];
return s;
}

void inti()
{
int i;
for(i=2;i<n;i++)
{
if(judge(str[i-2],str[i-1],str[i]))
modify(i,1);
}
}
int main()
{
int T,m,op,l,r,k,cnt=1;
char ch;
scanf("%d",&T);
while(T--)
{
scanf("%d%d",&n,&m);
scanf("%s",str);
memset(c,0,sizeof(c));
inti();
printf("Case %d:\n",cnt++);
while(m--)
{
scanf("%d",&op);
if(op==0)
{
scanf("%d%d",&l,&r);
if(r-l<2)
{
printf("0\n");
continue;
}
printf("%d\n",getsum(r)-getsum(l+1));
}
else
{
scanf("%d %c",&k,&ch);
if(str[k]==ch)
continue;
if(k>=2&&judge(str[k-2],str[k-1],str[k]))
modify(k,-1);
if(k>=2&&judge(str[k-2],str[k-1],ch))
modify(k,1);
if(k>=1&&k+1<n&&judge(str[k-1],str[k],str[k+1]))
modify(k+1,-1);
if(k>=1&&k+1<n&&judge(str[k-1],ch,str[k+1]))
modify(k+1,1);
if(k+2<n&&judge(str[k],str[k+1],str[k+2]))
modify(k+2,-1);
if(k+2<n&&judge(ch,str[k+1],str[k+2]))
modify(k+2,1);
str[k]=ch;
}
}
}
return 0;
}