线段树lazy模板 luogu3372

线段树写得很少，这么基本的算法还是要会的……

#include<bits/stdc++.h>
using namespace std;
inline long long read() {
    long long x = , f = ; char ch = getchar();
    while (ch<'' || ch>'') { if (ch == '-') f = -;ch = getchar(); }
    while (ch >= ''&&ch <= '') { x = x *  + ch - '';ch = getchar(); }
    return x*f;
}
const int maxn = ;
int n,m,op,_l,_r,k;
struct NODE{
    int l,r;
    long long lazy,val;
}node[maxn<<];
void pushup(int rt){
    node[rt].val = node[rt<<].val+node[rt<<|].val;
}
void pushdown(int rt){
    if(!node[rt].lazy) return ;
    int mid = node[rt].l+node[rt].r >>;
    node[rt<<].lazy += node[rt].lazy;
    node[rt<<|].lazy += node[rt].lazy;
    node[rt<<].val += node[rt].lazy*(mid-node[rt].l+);
    node[rt<<|].val += node[rt].lazy*(node[rt].r-mid);
    node[rt].lazy = ;

}
void build(int x,int l,int r){
    if((node[x].l = l) == (node[x].r = r)) return;
    int mid = node[x].l+node[x].r>>;
    build(x<<,l,mid),build(x<<|,mid+,r);
}
//单点更新
void add_one(int rt,int pos,long long val){
    if(node[rt].l == node[rt].r){
        node[rt].val+=val;
        return;
    }
    int mid = node[rt].l+node[rt].r>>;
    add_one(rt<<|pos>mid,pos,val);
    pushup(rt);
}
//区域更新
//所谓lazy就是只有当需要pushdown时才pushdown，query同
void add(int rt,int l,int r,int val){
    pushdown(rt); // 这一行的作用见 https://jecvay.com/2014/11/segment-tree-lazy-design.html
    if(node[rt].l>=l && node[rt].r<=r){
        node[rt].val+=val*(node[rt].r-node[rt].l+);
        node[rt].lazy += val;
        return ;
    }
    int mid = node[rt].l+node[rt].r>>;
    if(l<=mid) add(rt<<,l,r,val);
    if(r>mid) add(rt<<|,l,r,val);
    pushup(rt);
}
long long query(int rt,int l,int r){
    pushdown(rt);
    if(node[rt].l>=l && node[rt].r<=r) return node[rt].val;
    int mid = node[rt].l + node[rt].r >> ;
    long long ans = ;
    if(l<=mid) ans+=query(rt<<,l,r); // 易错
    if(r>mid) ans+=query(rt<<|,l,r);
    return ans;
}
int main(){
    n = read(), m = read();
    build(,,n);
    for(int i = ;i<n;i++) add_one(,i,read());
    for(int i = ;i<m;i++){
        op = read();_l = read()-; _r = read()-;
        if(op-) printf("%lld\n",query(,_l,_r));
        else{
            k = read();
            add(,_l,_r,k);
        }
    }
    return ;
}