void MaxLengthCore(char *cur,char *pre,int *max,int cursum)
{
if(*cur == '\0')
return ;
if(pre !=NULL && *cur == *pre)
{
++cursum;
if(cursum > *max)
*max = cursum;
pre = cur;
MaxLengthCore(++cur,pre,max,cursum);
}
else
{
cursum = 1;
pre = cur;
MaxLengthCore(++cur,pre,max,cursum);
}
}

int MaxLength(char
 
 *a,int n)
{
assert(a!=NULL && n>0);
int *max = (int*)malloc(sizeof(int));
*max = 1;
int cursum = 1;
char *pre = NULL;
MaxLengthCore(a,pre,max,cursum);
return *max;
}