Line segment tree for interval sum (template 2, lazy array)
Given an n-bit array and two operations:
- Operation 1: Add a value to all the numbers in a certain interval in the array
- Operation 2: Query the sum of all numbers in a certain interval in the array
Template question
struct SegmentTree{
int l,r;
LL sum,add;
#define l(x) tree[x].l
#define r(x) tree[x].r
#define sum(x) tree[x].sum
#define add(x) tree[x].add
}tree[maxn*4];
int a[maxn],n,m;
void build(int p,int l,int r){
l(p)=l,r(p)=r;
if(l==r) {
sum(p)=a[l];return;}
int mid=(l+r)/2;
build(p*2,l,mid);
build(p*2+1,mid+1,r);
sum(p)=sum(p*2)+sum(p*2+1);
}
void lazy(int p){
if(add(p)){
sum(p*2)+=add(p)*(r(p*2)-l(p*2)+1);
sum(p*2+1)+=add(p)*(r(p*2+1)-l(p*2+1)+1);
add(p*2)+=add(p);
add(p*2+1)+=add(p);
add(p)=0;
}
}
void change(int p,int l,int r,int z){
if(l<=l(p)&&r>=r(p)){
sum(p)+=(LL)z*(r(p)-l(p)+1);
add(p)+=z;
return;
}
lazy(p);
int mid=(l(p)+r(p))/2;
if(l<=mid) change(p*2,l,r,z);
if(r>mid) change(p*2+1,l,r,z);
sum(p)=sum(p*2)+sum(p*2+1);
}
LL ask(int p,int l,int r)
{
if(l<=l(p)&&r>=r(p)) return sum(p);
lazy(p);
int mid=(l(p)+r(p))/2;
LL ans=0;
if(l<=mid) ans+=ask(p*2,l,r);
if(r>mid) ans+=ask(p*2+1,l,r);
return ans;
}
int main()
{
cin>>n>>m;
for(int i=1;i<=n;i++)
scanf("%d",&a[i]);
build(1,1,n);
while(m--)
{
int op,x,y,z;
scanf("%d%d%d",&op,&x,&y);
if(x>y)swap(x,y);
if(op==1)
{
scanf("%d",&z);
change(1,x,y,z);
}
else printf("%lld\n",ask(1,x,y));
}
}