线段树结构体模板

线段树是一种维护区间和等功能的数据结构

struct SegTree{
	struct node{
		int l,r,sum,len,laz;
	}tree[N<<2];
	inline void pushdown(int u){
		int lson=u<<1,rson=lson|1;
		tree[lson].laz+=tree[u].laz;
		tree[rson].laz+=tree[u].laz;
		tree[lson].sum+=tree[lson].len*tree[u].laz;
		tree[rson].sum+=tree[rson].len*tree[u].laz;
		tree[lson].sum%=mod;
		tree[rson].sum%=mod;
		tree[u].laz=0; 
	}
	void build(int u,int l,int r,int w[]){
		tree[u].l=l,tree[u].r=r,tree[u].len=r-l+1,tree[u].sum=tree[u].laz=0;
		if(l==r){
			tree[u].sum=w[u];
			if(tree[u].sum>=mod)tree[u].sum%=mod;
			return;
		}
		int mid=(l+r)>>1,lson=u<<1,rson=lson|1;
		build(lson,l,mid,w);
		build(rson,mid+1,r,w);
		tree[u].sum=(tree[lson].sum+tree[rson].sum)%mod;
	}
	void update(int u,int l,int r,int k){
		if(l<=tree[u].l&&tree[u].r<=r){
			tree[u].laz+=k;
			tree[u].sum+=k*tree[u].len;
		}
		else{
			if(tree[u].laz)pushdown(u);
			int mid=(tree[u].l+tree[u].r)>>1,lson=u<<1,rson=lson|1;
			if(l<=mid)update(lson,l,r,k);
			if(r>mid)update(rson,l,r,k);
			tree[u].sum=(tree[lson].sum+tree[rson].sum)%mod;
		}
	}
	int query(int u,int l,int r){
		if(l<=tree[u].l && r<=tree[u].r){
			return tree[u].sum;
		}
		else{
			int res=0,mid=(tree[u].l+tree[u].r)>>1,lson=u<<1,rson=lson|1;
			if(tree[u].laz)pushdown(u);
			if(l<=mid)res=(res+query(lson,l,r))%mod;
			if(r>mid)res=(res+query(rson,l,r))%mod;
		}
	}
}tr;