线段树

这个可以用树状数组解决但是如果将一个区间的数字全部改为c一般只能用线段树

//线段树
#include<stdio.h>
#include<iostream>
using namespace std;
int a[100005];
int d[100005],b[100005];

inline void pushup(int p){
    d[p] = d[p<<1] + d[(p<<1)|1];
    return ;
}
inline void pushdown(int s,int t,int p)
{
    int mid = (s + t) >> 1;
    d[p<<1]+=(mid - s + 1) * b[p];
    d[(p<<1)|1] += (t - mid) * b[p];
    b[p<<1] = b[p];
    b[(p<<1)|1] = b[p];
    b[p] = 0;
}
void build(int l,int r,int p){
    if(l == r){
        d[p] = a[l];
        return ;
    }
    int mid = (l + r)>>1;
    build(l,mid,p<<1);
    build(mid + 1,r,p<<1|1);
    pushup(p);
}

inline void update(int l,int r,int c,int s,int t,int p){
    if(l <= s && t <= r){
        d[p] += (t - s + 1) *c;
        b[p] += c;
        return ;
    }
    if(b[p])pushdown(s,t,p);
    int mid = (s + t)>>1;
    if(l <= mid)update(l,r,c,s,mid,p<<1);
    if(r > mid)update(l,r,c,mid + 1,t,p<<1|1);
    pushup(p);
}
inline int getans(int l,int r,int s,int t,int p)
{
    int ans = 0;
    if(l <= s&&t <= r){
        return d[p];
    }
    //printf("%d %d\n",s,t);
    int mid = (s + t)>>1;
   // printf("%d\n",mid);
    if(b[p])pushdown(s,t,p);
    if(l <= mid)ans += getans(l,r,s,mid,p<<1);
    if(r > mid)ans += getans(l,r,mid + 1,t,p<<1|1);
    pushup(p);
    return ans;
}
int main()
{
    int n;
    scanf("%d",&n);
    for(int i = 1;i <= n;i++){
        scanf("%d",&a[i]);
    }
    build(1,n,1);
    int m;
    scanf("%d",&m);
    for(int i = 0;i < m;i++){
        int opt;
        scanf("%d",&opt);
        if(opt == 1){
            int a,b,c;
            scanf("%d%d%d",&a,&b,&c);
            update(a,b,c,1,n,1);
        }
        else{
            int a,b;
            scanf("%d%d",&a,&b);
            printf("%d\n",getans(a,b,1,n,1));
        }
    }
}