ZTL — 数据结构 — 线段树

区间加区间求和

class SegmentTree{
	private:
	#define lson (x<<1)
	#define rson ((x<<1)|1)
	ll t[maxn<<2], tag[maxn<<2] /*lazy tag*/, cnt;
	inline void pushup(int x){
		t[x] = (t[lson] + t[rson]);
	}
	inline void pushdown(int x, int l, int r){
		if(tag[x]){
			int mid = (l+r)>>1;
			t[lson] = (t[lson] + tag[x] * (mid-l+1));
			t[rson] = (t[rson] + tag[x] * (r-mid));
			tag[lson] = (tag[lson] + tag[x]);
			tag[rson] = (tag[rson] + tag[x]);
			tag[x] = 0;
			pushup(x);
		}
	}
	public:
	void build(int x, int l, int r, int *a){
		if(l == r){
			t[x] = a[++cnt];
		}else{
			int mid = (l+r) >> 1;
			build(lson, l, mid, a);
			build(rson, mid+1, r, a);
			pushup(x);
		}
	}
	void update(int x, int l, int r, int ql, int qr, ll k){
		if(ql <= l && r <= qr){
			t[x] = (t[x] + (r-l+1)*k);
			tag[x] = (tag[x] + k);
		}else{
			pushdown(x,l,r);
			int mid = (l+r) >> 1;
			if(ql <= mid) update(lson, l, mid, ql, qr, k);
			if(qr > mid) update(rson, mid+1, r, ql, qr, k);
			pushup(x);
		}
	}
	ll query(int x, int l, int r, int ql, int qr){
		if(ql <= l && r <= qr){
			return t[x];
		}else{
			pushdown(x, l, r);
			int mid = (l+r) >> 1; ll ret = 0;
			if(ql <= mid) ret = (ret + query(lson, l, mid, ql, qr));
			if(qr > mid) ret = (ret + query(rson, mid+1, r, ql, qr));
			return ret;
		}
	}
	#undef lson
	#undef rson
}