pku2777 线段树 (位运算加速)
有三个关键点，前两个和hdu1698一样
key1：记得将区间覆盖值置0时，将区间值赋给它的两个子区间
key2：当前区间cover不为0，即可return
key3：数据比较小，用位运算或操作，进行集合合并，加速过程。
代码
#include
<
stdio.h
>
#include
<
stdlib.h
>
#define
NN 100000
struct
node{
int
l, r, mid, cover;
}seg_tree[NN
*
8
];
void
Init(
int
l,
int
r,
int
id){
seg_tree[id].l
=
l;
seg_tree[id].r
=
r;
seg_tree[id].mid
=
(l
+
r)
>>
1
;
seg_tree[id].cover
=
1
;
if
(r
-
l
<=
1
){
return
;
}
Init(l, seg_tree[id].mid, id
*
2
);
Init(seg_tree[id].mid, r, id
*
2
+
1
);
}
void
Update(
int
l,
int
r,
int
key,
int
id){
if
(seg_tree[id].l
==
l
&&
seg_tree[id].r
==
r){
seg_tree[id].cover
=
key;
return
;
}
//
key 1
if
(seg_tree[id].cover
!=
0
){
seg_tree[id
*
2
].cover
=
seg_tree[id].cover;
seg_tree[id
*
2
+
1
].cover
=
seg_tree[id].cover;
seg_tree[id].cover
=
0
;
}
if
(r
<=
seg_tree[id].mid){
Update(l, r, key, id
*
2
);
}
else
if
(l
>=
seg_tree[id].mid){
Update(l, r, key, id
*
2
+
1
);
}
else
{
Update(l, seg_tree[id].mid, key, id
*
2
);
Update(seg_tree[id].mid, r, key, id
*
2
+
1
);
}
}
int
Search(
int
l,
int
r,
int
id){
//
key 2
if
(seg_tree[id].cover
>
0
){
return
1
<<
seg_tree[id].cover;
}
if
(r
<=
seg_tree[id].mid){
return
Search(l, r, id
*
2
);
}
else
if
(l
>=
seg_tree[id].mid){
return
Search(l, r, id
*
2
+
1
);
}
else
{
return
Search(l, seg_tree[id].mid, id
*
2
)
|
Search(seg_tree[id].mid, r, id
*
2
+
1
);
//
key 3
}
}
int
main(){
int
L, T, O, a, b, c, cnt, ans;
char
str[
3
];
scanf(
"
%d%d%d
"
,
&
L,
&
T,
&
O);
Init(
0
, L,
1
);
while
(O
--
){
scanf(
"
%s
"
, str);
if
(str[
0
]
==
'
C
'
){
scanf(
"
%d%d%d
"
,
&
a,
&
b,
&
c);
Update(a
-
1
, b, c,
1
);
}
else
{
scanf(
"
%d%d
"
,
&
a,
&
b);
ans
=
Search(a
-
1
, b,
1
);
cnt
=
0
;
while
(ans){
cnt
+=
ans
%
2
;
ans
/=
2
;
}
printf(
"
%d\n
"
, cnt);
}
}
//
system("pause");
}