优秀的 zkw 线段树讲解：

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存一份模板代码（区间修改、区间查询）：

/* zkw Segment Tree * Au: GG */#include 
    
     typedef long long ll;const int N=1e5+3;int n, m, zkw; ll t[N<<2], laz[N<<2];inline void update(int x, int y, ll val) {    ll l=0, r=0, f=1;    for (x+=zkw-1, y+=zkw+1; x^y^1; x>>=1, y>>=1, f<<=1) {        t[x]+=val*l, t[y]+=val*r;        if (~x&1) laz[x^1]+=val, t[x^1]+=val*f, l+=f;        if (y&1) laz[y^1]+=val, t[y^1]+=val*f, r+=f;    }    for (; x; x>>=1, y>>=1) t[x]+=val*l, t[y]+=val*r;}inline ll query(int x, int y) {    ll res=0, l=0, r=0, f=1;    for (x+=zkw-1, y+=zkw+1; x^y^1; x>>=1, y>>=1, f<<=1) {        if (laz[x]) res+=laz[x]*l;         if (laz[y]) res+=laz[y]*r;        if (~x&1) res+=t[x^1], l+=f;        if (y&1) res+=t[y^1], r+=f;    }    for (; x; x>>=1, y>>=1) res+=laz[x]*l, res+=laz[y]*r;    return res;}int main() {    scanf("%d%d", &n, &m);    for (zkw=1; zkw<=n+1; zkw<<=1);    for (int i=zkw+1; i<=zkw+n; i++) scanf("%lld", t+i);    for (int i=zkw-1; i>0; --i) t[i]=t[i<<1]+t[i<<1|1];    while (m--) {        int opt, a, b; ll c; scanf("%d%d%d", &opt, &a, &b);        if (opt<2) scanf("%lld", &c), update(a, b, c);         else printf("%lld\n", query(a, b));    }    return 0;}