點選檢視程式碼
#include<bits/stdc++.h>
#define lson id<<1
#define rson id<<1|1
using namespace std;
const int N=1e6+12000;
struct node{
int l,r,num;
int ma,mi;
}tr[N<<2];
int a[N];
int n,m;
string str;
int ans=0;
int from,to;
void build(int id,int l,int r){
tr[id].l=l;
tr[id].r=r;
if(l==r){
tr[id].num=a[l];
tr[id].ma=a[l];
tr[id].mi=a[l];
return;
}
int mid=(l+r)/2;
build(lson,l,mid);
build(rson,mid+1,r);
tr[id].num=tr[lson].num+tr[rson].num;
tr[id].ma=max(tr[lson].ma,tr[rson].ma);
tr[id].mi=min(tr[lson].mi,tr[rson].mi);
}
void update(int id,int x,int ad){
if(tr[id].l==tr[id].r){
tr[id].num+=ad;
tr[id].ma+=ad;
tr[id].mi+=ad;
return;
}
int mid=(tr[id].l+tr[id].r)/2;
if(x<=mid) update(lson,x,ad);
else update(rson,x,ad);
tr[id].num=tr[lson].num+tr[rson].num;
tr[id].ma=max(tr[lson].ma,tr[rson].ma);
tr[id].mi=min(tr[lson].mi,tr[rson].mi);
}
int getsum(int id,int l,int r){
if(r>=tr[id].r&&l<=tr[id].l){
return tr[id].num;
}
int mid=(tr[id].l+tr[id].r)/2;
if(mid<l) return getsum(rson,l,r);
else if(mid>=r) return getsum(lson,l,r);
else return getsum(lson,l,mid)+getsum(rson,mid+1,r);
}
int getmax(int id,int l,int r){
if(r>=tr[id].r&&l<=tr[id].l){
return tr[id].ma;
}
int maxn=0;
int mid=(tr[id].r+tr[id].l)/2;
if(mid<l) maxn=max(maxn,getmax(rson,l,r));
else if(mid>=r) maxn=max(maxn,getmax(lson,l,r));
else maxn=max({maxn,getmax(lson,l,mid),getmax(rson,mid+1,r)});
return maxn;
}
int getmin(int id,int l,int r){
if(r>=tr[id].r&&l<=tr[id].l){
return tr[id].ma;
}
int minn=0x7fffffff;
int mid=(tr[id].l+tr[id].r)/2;
if(mid<l) minn=min(minn,getmin(rson,l,r));
else if(mid>=r) minn=min(minn,getmin(lson,l,r));
else minn=min({minn,getmin(lson,l,mid),getmin(rson,mid+1,r)});
return minn;
}
int main(){
cin>>n;
for(int i=1;i<=n;i++){
cin>>a[i];
}
cin>>m;
if(n) build(1,1,n);
for(int i=1;i<=m;i++){
cin>>str>>from>>to;
if(str=="ADD"){
update(1,from,to);
}
else{
cout<<getsum(1,from,to)<<endl;
}
}
}
幾個注意點
1.更新和建樹跑到葉子時要return
if(tr[id].l==tr[id].r){
tr[id].num+=ad;
tr[id].ma+=ad;
tr[id].mi+=ad;
return;
}
if(l==r){
tr[id].num=a[l];
tr[id].ma=a[l];
tr[id].mi=a[l];
return;
}
2.關於取等
if(mid<l) return getsum(rs,l,r);
else if(mid>=r) return getsum(ls,l,r);
else return getsum(ls,l,mid)+getsum(rs,mid+1,r);
分別對應以上三行程式碼，因為我們是將l到mid定為lson，mid+1到r定為rson,所以查詢的左邊界要大於mid才能完全在右區間，而右邊界僅需小於等於
3.區間處理（lazy標記）
點選檢視程式碼
#include<bits/stdc++.h>
#define lson id<<1
#define rson id<<1|1
using namespace std;
const int N=1e6+1200;
int a[N];
int n,m;
struct node{
int l,r,lazy,num;
}tr[N<<2];
void build(int id,int l,int r){
tr[id].l=l;
tr[id].r=r;
if(l==r){
tr[id].num=a[l];
return;
}
int mid=(l+r)/2;
build(lson,l,mid);
build(rson,mid+1,r);
tr[id].num=tr[lson].num+tr[rson].num;
}
void pushup(int id){
tr[lson].lazy+=tr[id].lazy;
tr[rson].lazy+=tr[id].lazy;
tr[lson].num+=(tr[lson].r-tr[lson].l+1)*tr[id].lazy;
tr[rson].num+=(tr[rson].r-tr[rson].l+1)*tr[id].lazy;
tr[id].lazy=0;
}
void update(int id,int l,int r,int ad){
if(l>tr[id].r||r<tr[id].l){
return;
}
if(tr[id].r<=r&&tr[id].l>=l){
tr[id].num+=ad*(tr[id].r-tr[id].l+1);
tr[id].lazy+=ad;
return;
}
int mid=(tr[id].l+tr[id].r)/2;
pushup(id);
update(lson,l,r,ad);
update(rson,l,r,ad);
tr[id].num=tr[lson].num+tr[rson].num;
}
int getsum(int id,int l,int r){
if(l>tr[id].r||r<tr[id].l){
return 0;
}
if(tr[id].r<=r&&tr[id].l>=l){
return tr[id].num;
}
int mid=(tr[id].l+tr[id].r)/2;
pushup(id);
return getsum(lson,l,mid)+getsum(rson,mid+1,r);
}
int main(){
string str;
int from,to,w;
cin>>n;
for(int i=1;i<=n;i++){
cin>>a[i];
}
build(1,1,n);
cin>>m;
for(int i=1;i<=m;i++){
cin>>str;
if(str=="SUM"){
cin>>from>>to;
cout<<getsum(1,from,to)<<endl;
}
else {
cin>>from>>to>>w;
update(1,from,to,w);
}
}
}
void pushup(int id){
tr[lson].lazy+=tr[id].lazy;
tr[rson].lazy+=tr[id].lazy;//處理id以及它的子樹對應的總和，將子樹以及它的子子樹的處理先放置一邊
tr[lson].num+=(tr[lson].r-tr[lson].l+1)*tr[id].lazy;
tr[rson].num+=(tr[rson].r-tr[rson].l+1)*tr[id].lazy;
tr[id].lazy=0;//處理完清零
}
（畫的不是太好，但基本是這麼個意思）