[Template] segment tree (luogu P3372)

#include <cstdio>
#define N 1000010
typedef long long ll;

ll n, m, opt, p, q, s;
ll a[N], add[N << 2], sum[N << 2];

void build(ll i, ll l, ll r){　　　　//建树
    if(l == r){
        sum[i] = a[l];
        return;
    }

    ll mid = (l + r) >> 1;
    build(i << 1, l, mid);
    build(i << 1 | 1, mid + 1, r);

    sum[i] = sum[i << 1] + sum[i << 1 | 1];
}

void plu(ll i, ll l, ll r, ll v){　　//加法运算
    add[i] += v;
    sum[i] += (r - l + 1) * v;
}

void pushdown(ll i, ll l, ll r, ll mid){　　//维护 Lazy-tag
    if(add[i] == 0) return;

    plu(i << 1, l, mid, add[i]);
    plu(i << 1 | 1, mid + 1, r, add[i]);

    add[i] = 0;
}

ll query(ll i, ll l, ll r, ll x, ll y){　　　//询问区间和
    if(l >= x && r <= y) return sum[i];

    ll mid = (l + r) >> 1, ans = 0;
    pushdown(i, l, r, mid);

    if(x <= mid) ans += query(i << 1, l, mid, x, y);
    if(y > mid) ans += query(i << 1 | 1, mid + 1, r, x, y);

    return ans;
}

void modify(ll i, ll l, ll r, ll x, ll y, ll v){　　//更新区间
    if(l >= x && r <= y){
        plu(i, l, r, v);
        return;
    }

    ll mid = (l + r) >> 1;
    pushdown(i, l, r, mid);

    if(x <= mid) modify(i << 1, l, mid, x, y, v);
    if(y > mid) modify(i << 1 | 1, mid + 1, r, x, y, v);

    sum[i] = sum[i << 1] + sum[i << 1 | 1];
}

int main(){

    scanf("%lld%lld", &n, &m);
    for(ll i=1; i<=n; i++) scanf("%lld", &a[i]);
    build(1, 1, n);

    while(m--){
        scanf("%lld", &opt);

        if(opt == 1){
            scanf("%lld%lld%lld", &p, &q, &s);
            modify(1, 1, n, p, q, s);
        }

        else{
            scanf("%lld%lld", &p, &q);
            printf("%lld\n", query(1, 1, n, p, q));
        }
    }
    return 0;
}