求助 蒟蒻第一次敲线段树：[题目](https://www.luogu.com.cn/problem/P3372) 应该是ask_the_answer函数出了错，但哪里错了呀，调了好久（哭） #include<bits/stdc++.h> using namespace std; typedef long long ll; ll n,m,a[100010]; struct node{ ll l,r; ll sum; ll lazy_flag; }c[400050]; void build(ll x,ll l,ll r){ c[x].l=l; c[x].r=r; if(l==r){ c[x].sum=a[l]; return ; } ll mid=(l+r)>>1; c[x*2].sum=(x*2,l,mid); c[x*2+1].sum=(x*2+1,mid+1,r); c[x].sum=c[x*2].sum+c[x*2+1].sum; } void lazy_down(ll x){ if(c[x].lazy_flag!=0){ ll add=c[x].lazy_flag; c[x*2].sum+=add*(c[x*2].r-c[x*2].l+1); c[x*2].lazy_flag+=add; c[x*2+1].sum=add*(c[x*2+1].r-c[x*2+1].l+1); c[x*2+1].lazy_flag+=add; c[x].lazy_flag=0; } } void find(ll i,ll l,ll r,ll k){ if(c[i].l>=l&&c[i].r<=r){ c[i].lazy_flag+=k; c[i].sum+=k*(c[i].r-c[i].l+1); return ; } lazy_down(i); ll mid=(c[i].l+c[i].r)>>1; if(l<=mid){ find(i*2,l,r,k); } if(r>mid){ find(i*2+1,l,r,k); } c[i].sum=c[i*2].sum+c[i*2+1].sum; } ll ask_the_answer(ll i,ll l,ll r){ ll ans=0; if(c[i].l>=l&&c[i].r<=r){ return c[i].sum; } lazy_down(i); ll mid=(c[i].l+c[i].r)>>1; if(l<=mid){ ans+=ask_the_answer(i*2,l,r); } if(r>mid){ ans+=ask_the_answer(i*2+1,l,r); } return ans; } int main(){ cin>>n>>m; for(int i=1;i<=n;i++){ scanf("%lld",&a[i]); } build(1,1,n); ll k,x,y,z; for(int i=1;i<=m;i++){ scanf("%lld%lld%lld",&k); if(k==1){ scanf("%lld%lld%lld",&x,&y,&z); find(1,x,y,z); }else{ scanf("%lld%lld",&x,&y); cout<<ask_the_answer(1,x,y)<<endl; } } return 0; }