纪念一下第一次写的线段树了喽（对应洛谷3372）

#include <bits/stdc++.h>  
using namespace std;  
typedef long long ll;  
struct tree{  
    ll data;  
    ll l;  
    ll r;  
    ll lazy=0;  
};  
tree a[400040];  
ll b[100010];  
ll wh[400040];  
void pushdown(ll i){  
    if(a[i].lazy!=0){  
        if(a[i].l!=a[i].r){  
            ll ch=i<<1;  
            a[ch].lazy+=a[i].lazy;  
            a[ch+1].lazy+=a[i].lazy;  
            a[i].data+=(a[i].r-a[i].l+1)*a[i].lazy;  
        }  
        else a[i].data+=a[i].lazy;  
        a[i].lazy=0;  
    }  
}  
void update(ll i){  
    ll ch=i<<1;  
    pushdown(ch);  
    pushdown(ch+1);  
    a[i].data=a[ch].data+a[ch+1].data;  
    return ;  
}  
void build(ll l,ll r,ll i){  
    a[i].l=l;  
    a[i].r=r;  
    if(l==r){  
        a[i].data=b[l];  
        return ;  
    }  
    ll ch=i<<1;  
    ll mid=(l+r)>>1;  
    build(l,mid,ch);  
    build(mid+1,r,ch+1);  
    if(l!=r)update(i);  
}  
void change(ll l,ll r,ll i,ll add){  
    pushdown(i);  
    if(a[i].l>=l&&a[i].r<=r){  
        a[i].lazy+=add;  
        return ;  
    }  
    ll mid=(a[i].l+a[i].r)>>1;  
    ll ch=i<<1;  
    if(r<=mid){  
        change(l,r,ch,add);  
    }  
    else if(l>mid){  
        change(l,r,ch+1,add);  
    }  
    else{  
        change(l,mid,ch,add);  
        change(mid+1,r,ch+1,add);  
    }  
    update(i);  
}  
ll getsum(ll l,ll r,ll i){  
    pushdown(i);  
    if(a[i].l>=l&&a[i].r<=r){  
        return a[i].data;  
    }  
    ll mid=(a[i].l+a[i].r)>>1;  
    ll ch=i<<1;  
    if(r<=mid){  
        return getsum(l,r,ch);  
    }  
    else if(l>mid){  
        return getsum(l,r,ch+1);  
    }  
    else return getsum(l,mid,ch)+getsum(mid+1,r,ch+1);  
}  
int main(){  
    ll n,m;  
    scanf("%lld%lld",&n,&m);  
    ll i;  
    for(i=1;i<=n;i++){  
        scanf("%lld",&b[i]);  
    }  
    build(1,n,1);  
    while(m--){  
        ll way;  
        scanf("%d",&way);  
        switch(way){  
            case 1:{  
                ll l,r,k;  
                scanf("%lld%lld%lld",&l,&r,&k);  
                change(l,r,1,k);  
                break;  
            }  
            case 2:{  
                ll x,y;  
                scanf("%lld%lld",&x,&y);  
                cout<<getsum(x,y,1)<<endl;  
                break;  
            }  
        }  
    }  
    system("pause");  
}