osfly @ 2022-04-08 13:34:42
#include<cstdio>
#define int long long
int a[500010];
struct seg
{
struct node
{
int sum,ml,mr;
int val;
int l,r;
}t[500010*4];
int max(int a,int b)
{
return a>b?a:b;
}
void pushup(int k)
{
t[k].sum=t[2*k].sum+t[2*k+1].sum;
t[k].ml=max(t[2*k].ml,t[2*k].sum+t[2*k+1].ml);
t[k].mr=max(t[2*k+1].mr,t[2*k+1].sum+t[2*k].mr);
t[k].val=max(max(t[2*k].val,t[2*k+1].val),t[2*k].mr+t[2*k+1].ml);
}
void build(int k,int l,int r)
{
t[k].l=l,t[k].r=r;
if(l==r)
{
t[k].val=t[k].ml=t[k].mr=t[k].sum=a[l];
return ;
}
int mid=(l+r)>>1;
build(2*k,l,mid);
build(2*k+1,mid+1,r);
pushup(k);
}
void update(int k,int x,int num)
{
if(t[k].l==t[k].r)
{
t[k].val=t[k].ml=t[k].mr=t[k].sum=num;
return ;
}
int mid=(t[k].l+t[k].r)>>1;
if(x<=mid) update(2*k,x,num);
else update(2*k+1,x,num);
pushup(k);
}
node query(int k,int l,int r)
{
if(t[k].l>=l&&t[k].r<=r) return t[k];
int mid=(t[k].l+t[k].r)>>1;
if(r<=mid) return query(2*k,l,r);
if(l>mid) return query(2*k+1,l,r);
node re,left=query(2*k,l,r),right=query(2*k+1,l,r);
re.sum=left.sum+right.sum;
re.ml=max(left.ml,left.sum+right.ml);
re.mr=max(right.mr,right.sum+left.mr);
re.val=max(max(left.sum,right.sum),left.mr+right.ml);
return re;
}
}tree;
int n,m;
void swap(int &a,int &b)
{
int tmp=a;
a=b;
b=tmp;
}
signed main()
{
scanf("%lld%lld",&n,&m);
for(int i=1;i<=n;i++) scanf("%lld",&a[i]);
tree.build(1,1,n);
while(m--)
{
int op,l,r;
scanf("%lld%lld%lld",&op,&l,&r);
if(op==1)
{
if(l>r) swap(l,r);
printf("%lld\n",tree.query(1,l,r).val);
}
else tree.update(1,l,r);
}
return 0;
}
A#1,其余全WA,求助
by for_to @ 2022-04-09 17:38:14
by osfly @ 2022-04-09 18:36:01
@Early_summer
刚刚被爸妈强制进行了一会whk,有点晚回复,抱歉
确实是眼瞎了(
A了,感谢大佬