推荐几篇好的线段树解析以及模板题

https://www.cnblogs.com/xenny/p/9801703.html
https://www.luogu.com.cn/problem/P3372

C++ 代码

#include <bits/stdc++.h>
using namespace std;
const int maxn=100010;
int a[210000],n,m,k,x,y;
struct node
{
    int l;
    int r;
    int sum;
    //int lazy;
} tree[4*maxn+2];
//void push_down(int u)
//{
//    if(tree[u].sum)
//    {
//        tree[u*2].sum+=tree[u].lazy*(tree[u*2].r-tree[u*2].l+1);
//        tree[u*2+1].sum+=tree[u].lazy*(tree[u*2+1].r-tree[u*2+1].l+1);
//        tree[u*2].lazy+=tree[u].lazy;
//        tree[u*2+1].lazy+=tree[u].lazy;
//        tree[u].lazy=0;
//    }
//}
void buildtree(int u,int left,int right)
{
    tree[u].l=left;
    tree[u].r=right;
    if(left==right)
    {
        tree[u].sum=a[left];
        return;
    }
    int mid=(left+right)>>1;
    buildtree(u<<1,left,mid);
    buildtree(u<<1|1, mid+1,right);
    tree[u].sum=tree[u<<1].sum+tree[u<<1|1].sum;
}
void change(int u,int left,int right,int x,int y)
{
    if(left==right)
    {
        a[x]+=y;
        tree[u].sum+=y;
        return;
    }
    int mid=(left+right)>>1;
    if(x<=mid)
    {
        change(u<<1,left,mid,x,y);
    }
    else
    {
        change(u<<1|1,mid+1,right,x,y);
    }
    tree[u].sum=tree[u<<1].sum+tree[u<<1|1].sum;
}
int check(int u,int x,int y)
{
    if(x<=tree[u].l&&y>=tree[u].r)
    {
        return tree[u].sum;
    }
    //push_down(u);
    int mid=(tree[u].l+tree[u].r)>>1;
    int t=0;
    if(x<=mid)
    {
        t+=check(u<<1,x,y);
    }
    if(y>mid)
    {
        t+=check(u<<1|1,x,y);
    }
    return t;
}
int main()
{
    ios::sync_with_stdio(false);
    cin>>m>>n;
    for(int i=1; i<=m; i++)
    {
        cin>>a[i];
    }
    buildtree(1,1,m);
    for(int i=1; i<=n; i++)
    {
        cin>>k>>x>>y;
        if(k==0)
        {
            int temp=check(1,x,y);
            cout<<temp<<endl;
        }
        if(k==1)
        {
            change(1,1,m,x,y);
        }
    }
    return 0;
}