HDU 1754 I Hate It
/*
线段树
更新节点,区间最值
*/
#include
<
stdio.h
>
#include
<
stdlib.h
>
const
int
MAXN
=
200001
;
int
MAX(
int
x,
int
y){
return
x
>
y
?
x : y;
}
struct
segTree{
int
L,R;
int
max;
};
segTree tree[MAXN
<<
2
];
int
st[MAXN];
void
bulid(
int
left,
int
right,
int
t){
tree[t].L
=
left;
tree[t].R
=
right;
if
( left
==
right )
tree[t].max
=
st[left];
else
{
int
mid
=
( left
+
right )
>>
1
;
bulid(left, mid,
2
*
t);
bulid(mid
+
1
, right,
2
*
t
+
1
);
tree[t].max
=
MAX(tree[
2
*
t].max, tree[
2
*
t
+
1
].max);
}
}
void
updata(
int
num,
int
score,
int
t){
if
(tree[t].L
==
num
&&
tree[t].R
==
num){
tree[t].max
=
score;
}
else
if
(tree[t].L
<
tree[t].R ){
int
mid
=
(tree[t].L
+
tree[t].R)
>>
1
;
if
(num
>
mid){
updata(num, score,
2
*
t
+
1
);
}
if
(num
<=
mid){
updata(num, score,
2
*
t);
}
tree[t].max
=
MAX(tree[
2
*
t].max, tree[
2
*
t
+
1
].max);
}
}
int
query(
int
left,
int
right,
int
t){
if
(left
==
tree[t].L
&&
right
==
tree[t].R ){
return
tree[t].max;
}
else
if
(tree[t].L
<
tree[t].R ){
int
mid
=
(tree[t].L
+
tree[t].R )
>>
1
;
if
( right
<=
mid ){
return
query(left, right, t
*
2
);
}
else
if
( left
>
mid ){
return
query(left, right, t
*
2
+
1
);
}
else
{
return
MAX(query(left, mid, t
*
2
), query(mid
+
1
, right, t
*
2
+
1
));
}
}
return
0
;
}
int
main(){
//
freopen("1012.txt","r",stdin);
int
n, m, a, b;
char
C;
while
(scanf(
"
%d%d
"
,
&
n,
&
m)
!=
EOF){
for
(
int
i
=
1
; i
<=
n; i
++
)
scanf(
"
%d
"
,
&
st[i]);
bulid(
1
,n,
1
);
getchar();
//
这里错
while
(m
--
){
scanf(
"
%c
"
,
&
C);
if
(C
==
'
Q
'
){
scanf(
"
%d%d
"
,
&
a,
&
b);
printf(
"
%d\n
"
,query(a,b,
1
));
}
else
{
scanf(
"
%d%d
"
,
&
a,
&
b);
updata(a,b,
1
);
}
getchar();
}
}
return
0
;
}