问题标题: 洛谷：刚学OI的萌新求助QwQ

【模板】线段树 2

30分，WA7个点。

#include <iostream>
using namespace std;
#define it long long
struct xianduan{
    it l,r,sum,sum2;
};
xianduan tree[1000001];
it a[1000001],f[1000001];
it tree2[1000001],tree3[1000001];
int mod;
void build(it x,it l,it r)
{
    tree[x].l=l;
    tree[x].r=r;
    tree3[x]=1;
    if(l==r)
    {
        tree[x].sum=a[l];
        tree[x].sum%=mod;
        return;
    }
    build(x*2,l,(l+r)>>1);
    build(x*2+1,1+((l+r)>>1),r);
    tree[x].sum=tree[x*2].sum+tree[x*2+1].sum;
    tree[x].sum%=mod;
}
void pushdown(it x)
{
    it mid=(tree[x].l+tree[x].r)/2;
    tree[x*2].sum=(tree[x*2].sum*tree3[x]+tree2[x]*(mid-tree[x].l+1))%mod;
    tree[x*2+1].sum=(tree[x*2+1].sum*tree3[x]+tree2[x]*(tree[x].r-mid))%mod;
    tree3[x*2]=(tree3[x*2]*tree3[x])%mod;
    tree3[x*2+1]=(tree3[x*2+1]*tree3[x])%mod;
    tree2[x*2]=(tree2[x*2]*tree3[x]+tree2[x])%mod;
    tree2[x*2+1]=(tree2[x*2+1]*tree3[x]+tree2[x])%mod;
    tree3[x]=1;
    tree2[x]=0;
}
void update(it x,it l,it r,it k)
{
    if(tree[x].l>=l&&tree[x].r<=r)
    {
        tree[x].sum=(tree[x].sum+(tree[x].r-tree[x].l+1)*k)%mod;
        tree2[x]=(tree2[x]+k)%mod;
        return;
    }
    if(tree[x].l>r||tree[x].r<l)
        return;
    it mid=(tree[x].r+tree[x].l)/2;
    pushdown(x);
    update(x*2,l,r,k);
    update(x*2+1,l,r,k);
    tree[x].sum=(tree[x*2].sum+tree[x*2+1].sum)%mod;
}
void update1(it x,it l,it r,it k)
{
    if(tree[x].l>=l&&tree[x].r<=r)
    {
        tree[x].sum=(tree[x].sum*k)%mod;
        tree3[x]=(tree3[x]*k)%mod;
        tree2[x]=(tree2[x]*k)%mod;
        return;
    }
    if(tree[x].l>r||tree[x].r<l)
        return;
    it mid=(tree[x].r+tree[x].l)/2;
    pushdown(x);
    update1(x*2,l,r,k);
    update1(x*2+1,l,r,k);
    tree[x].sum=(tree[x*2].sum+tree[x*2+1].sum)%mod;
}
it query(it x,it l,it r)
{
    if(tree[x].l>=l&&tree[x].r<=r)
        return tree[x].sum;
    if(tree[x].l>r||tree[x].r<l)
        return 0;
    if(tree2[x])pushdown(x);
    return (query(x*2,l,r)+query(x*2+1,l,r))%mod;
}
int main()
{
    it n,m;
    cin>>n>>m>>mod;
    for(it i=1;i<=n;i++)
    cin>>a[i];
    build(1,1,n);
    for(int i=1;i<=m;i++)
    {
        it a,b,c;
        int t;
        cin>>t>>a>>b;
        if(t==2)
        {
            cin>>c;
            update(1,a,b,c);
        }
        else if(t==3) cout<<query(1,a,b)%mod<<endl;
        else 
        {
            cin>>c;
            update1(1,a,b,c);
        }
    }
    return 0;
}

现在弱到连线段树板子都不会了