HDU 4046 panda line segment tree

In the five online games, a large number of Line Segment trees were created, and each time they were sitting there, they were dummies ..

It seems that we need to chew on the Line Segment tree ..

 

# Include <iostream>
# Include <string>
# Define maxn50010
# Define lson L, M, RT <1
# Define rson m + 1, R, RT <1 | 1
Using namespace STD;
Int sum [maxn * 4];
Char STR [maxn];
Int A [maxn];
Void pushup (int rt)
{
Sum [RT] = sum [RT <1] + sum [RT <1 | 1];
}
Void build (int l, int R, int RT)
{
If (L = r ){
Sum [RT] = A [l];
Return;
}
Int M = (L + r)> 1;
Build (lson );
Build (rson );
Pushup (RT );
}

Void Update (int p, int add, int L, int R, int RT)
{
If (L = r)
{
Sum [RT] = add;
Return;
}
Int M = (L + r)> 1;
If (P <= m) Update (p, add, lson );
Else Update (p, add, rson );
Pushup (RT );
}
Int query (int l, int R, int L, int R, int RT)
{
If (L <= L & R <= r ){
Return sum [RT];
}
Int M = (L + r)> 1;
Int ret = 0;
If (L <= m) RET + = query (L, R, lson );
If (r> m) RET + = query (L, R, rson );
Return ret;
}
Int main ()
{
Int cas, T = 0, n, m, R, L, C;
Char st;
Scanf ("% d", & CAS );
While (CAS --)
{
Scanf ("% d", & N, & M );
Scanf ("% s", STR );
Memset (A, 0, sizeof ());
Printf ("case % d: \ n", ++ t );
For (INT I = 2; I <n; I ++) // indicates whether a substring whose length ends with this subscript is 3.
{
If (STR [I]! = 'W ')
A [I] = 0;
Else if (STR [I-1] = 'B' & STR [I-2] = 'W ')
A [I] = 1;
}
Build (0, N, 1 );
While (M --)
{
Scanf ("% d", & C );
If (C = 0)
{
Scanf ("% d", & L, & R );
L + = 2;
If (L> r) printf ("0 \ n ");
Else
Printf ("% d \ n", query (L, R, 0, N, 1 ));
}
Else
{
Scanf ("% d % C", & L, & St );
If (STR [l] = sT) // if you want to use the same character as the original one, you do not need to modify it.
Continue;
STR [l] = sT;
If (L> = 2 & STR [L-2] = 'W' & STR [L-1] = 'B' & STR [l] = 'W ')
{
If (A [l] = 0) // if it is a non-conforming string before modification, update
Update (L, 1, 0, N, 1 );
A [l] = 1;
}
Else if (L> = 2 & A [l] = 1) // if it is a required string before modification, update
{
Update (L, 0, 0, N, 1 );
A [l] = 0;
}
If (L> = 1 & STR [l] = 'B' & STR [L-1] = 'W' & STR [L + 1] = 'W ')
{
If (A [L + 1] = 0)
Update (L + 1, 1, 0, N, 1 );
A [L + 1] = 1;
}
Else if (L <n-1 & L> = 1 & A [L + 1] = 1) A [L + 1] = 0, update (L +, 0, N, 1 );
If (STR [l] = 'W' & STR [L + 1] = 'B' & STR [L + 2] = 'W ')
{
If (A [L + 2] = 0)
Update (L + 2, 1, 0, N, 1 );
A [L + 2] = 1;
}
Else
If (L <N-2 & A [L + 2] = 1)
A [L + 2] = 0, update (L + 2, 0, 0, N, 1 );
}
}
}
Return 0;
}