[板子]segTree

segTree

参考：http://www.cnblogs.com/TenosDoIt/p/3453089.html#c

初学者建议先参考上面“一步一步理解线段树”学习理论。

在这里Code分别为区间求和&区间求积的做法。

分别对应OJ luogu的3372和3373

1.区间和

 #include<cstdio>
 #include<cmath>
 #include<iostream>
 #include<algorithm>
 using namespace std;
 struct node{
     long long val,lazytag;
 }segTree[*+];
 ];
 int n,m,t,x,y,k;
 void build(int root,long long arr[],int istart,int iend){//建树
     segTree[root].lazytag=;
     if(istart==iend){
         segTree[root].val=arr[istart];
     }else{
         ;
         build(root*,arr,istart,mid);
         build(root*+,arr,mid+,iend);
         segTree[root].val=segTree[root*].val+segTree[root*+].val;
     }
 }
 void pushDown(int root,int start,int end){//插入懒标记
     ){
         segTree[root*].lazytag+=segTree[root].lazytag;
         segTree[root*+].lazytag+=segTree[root].lazytag;
         ;
         segTree[root*].val+=segTree[root].lazytag*(mid-start+);
         segTree[root*+].val+=segTree[root].lazytag*(end-mid);
         segTree[root].lazytag=;
     }
 }
 long long query(int root,int nstart,int nend,int qstart,int qend){//查询区间
     if(qstart>nend||qend<nstart){
         ;
     }if(qstart<=nstart&&qend>=nend){
         return segTree[root].val;
     }
     pushDown(root,nstart,nend);
     ;
     ,nstart,mid,qstart,qend)+query(root*+,mid+,nend,qstart,qend);
 }
 void update(int root,int nstart,int nend,int ustart,int uend,int addval){//赋值
     if(ustart>nend||uend<nstart){
         return;
     }if(ustart<=nstart&&uend>=nend){
         segTree[root].lazytag+=addval;
         segTree[root].val+=addval*(nend-nstart+);
         return;
     }
     pushDown(root,nstart,nend);
     ;
     update(root*,nstart,mid,ustart,uend,addval);
     update(root*+,mid+,nend,ustart,uend,addval);
     segTree[root].val=segTree[root*].val+segTree[root*+].val;
 }
 int main(){
     scanf("%lld%lld",&n,&m);
     ;i<=n;i++){
         scanf("%lld",&a[i]);
     }
     build(,a,,n);
     ;i<=m;i++){
         scanf("%lld",&t);
         ){
             scanf("%lld%lld%lld",&x,&y,&k);
             update(,,n,x,y,k);
         }){
             scanf("%lld%lld",&x,&y);
             printf(,,n,x,y));
         }
     }
 }

2.区间积

在这里要点几个点注意：

1：tag2的初始值为1；

2：pushdown里先tag2后tag1（先乘后加）；

3：对tag2进行push需要先把tag1*tag2，tag2*tag2，val*tag2，最后别忘了tag2=1；

4：tag2不需要乘区间，原因是:a*(b+c)=a*b+a*c，乘法分配律；

 #include<cstdio>
 #include<cmath>
 #include<iostream>
 #include<algorithm>
 using namespace std;
 struct node{
     long long val,lazytag,lazytag2;
 }segTree[*+];
 ];
 long long n,m,t,x,y,k,p;
 void build(int root,long long arr[],int istart,int iend){//建树
     segTree[root].lazytag=;
     segTree[root].lazytag2=;
     if(istart==iend){
         segTree[root].val=arr[istart];
     }else{
         ;
         build(root*,arr,istart,mid);
         build(root*+,arr,mid+,iend);
         segTree[root].val=segTree[root*].val+segTree[root*+].val;
     }
 }
 void pushDown(int root,int start,int end){//插入懒标记
     **){**
         segTree[root*].lazytag=(segTree[root*].lazytag*segTree[root].lazytag2)%p;
         segTree[root*+].lazytag=(segTree[root*+].lazytag*segTree[root].lazytag2)%p;
         segTree[root*].lazytag2=(segTree[root*].lazytag2*segTree[root].lazytag2)%p;
         segTree[root*+].lazytag2=(segTree[root*+].lazytag2*segTree[root].lazytag2)%p;
         ;
         segTree[root*].val=(segTree[root*].val*(segTree[root].lazytag2))%p;
         segTree[root*+].val=(segTree[root*+].val*(segTree[root].lazytag2))%p;
         segTree[root].lazytag2=;
     }
     ){
         segTree[root*].lazytag+=segTree[root].lazytag;
         segTree[root*+].lazytag+=segTree[root].lazytag;
         ;
         segTree[root*].val+=segTree[root].lazytag*(mid-start+);
         segTree[root*+].val+=segTree[root].lazytag*(end-mid);
         segTree[root].lazytag=;
     }
 }
 long long query(int root,int nstart,int nend,int qstart,int qend){//查询区间
     if(qstart>nend||qend<nstart){
         ;
     }if(qstart<=nstart&&qend>=nend){
         return segTree[root].val;
     }
     pushDown(root,nstart,nend);
     ;
     ,nstart,mid,qstart,qend)+query(root*+,mid+,nend,qstart,qend);
 }
 void update(int root,int nstart,int nend,int ustart,int uend,int addval){//赋值
     if(ustart>nend||uend<nstart){
         return;
     }if(ustart<=nstart&&uend>=nend){
         segTree[root].lazytag+=addval;
         segTree[root].val+=addval*(nend-nstart+);
         return;
     }
     pushDown(root,nstart,nend);
     ;
     update(root*,nstart,mid,ustart,uend,addval);
     update(root*+,mid+,nend,ustart,uend,addval);
     segTree[root].val=segTree[root*].val+segTree[root*+].val;
 }
 **void tupdate(int root,int nstart,int nend,int ustart,int uend,int addval){//赋值(chengfa**
     if(ustart>nend||uend<nstart){
         return;
     }if(ustart<=nstart&&uend>=nend){
         segTree[root].lazytag=(segTree[root].lazytag*addval)%p;
         segTree[root].lazytag2=(segTree[root].lazytag2*addval)%p;
         segTree[root].val=(segTree[root].val*addval)%p;
         return;
     }
     pushDown(root,nstart,nend);
     ;
     tupdate(root*,nstart,mid,ustart,uend,addval);
     tupdate(root*+,mid+,nend,ustart,uend,addval);
     segTree[root].val=segTree[root*].val+segTree[root*+].val;
 }
 int main(){
     scanf("%lld%lld%lld",&n,&m,&p);
     ;i<=n;i++){
         scanf("%lld",&a[i]);
     }
     build(,a,,n);
     ;i<=m;i++){
         scanf("%lld",&t);
         ){
             scanf("%lld%lld%lld",&x,&y,&k);
             update(,,n,x,y,k);
         }){
             scanf("%lld%lld",&x,&y);
             printf(,,n,x,y)%p);
         }){
             scanf("%lld%lld%lld",&x,&y,&k);
             tupdate(,,n,x,y,k);
         }
     }
     ;
 }

并且感谢will7101的帮助