本文共 937 字，大约阅读时间需要 3 分钟。

#include
   
    using namespace std;typedef long long ll;const int maxn=3e5+1; int a[maxn],b[maxn],pos[maxn];struct node{   	int l,r,lazy,sum;}tree[maxn<<2];void pushup(int x){   	tree[x].sum=max(tree[x<<1].sum,tree[x<<1|1].sum);}void pushdown(int x){   	if(tree[x].lazy)	{   		tree[x<<1].sum+=tree[x].lazy;		tree[x<<1|1].sum+=tree[x].lazy;		tree[x<<1].lazy+=tree[x].lazy;		tree[x<<1|1].lazy+=tree[x].lazy;		tree[x].lazy=0;	}}void build(int x,int l,int r){   	tree[x].l=l;tree[x].r=r;	if(l==r){   		tree[x].lazy=tree[x].sum=0;return ;	}	int mid=(l+r)>>1;	build(x<<1,l,mid);	build(x<<1|1,mid+1,r);	pushup(x);}void update(int x,int l,int r,int v){   	if(l<=tree[x].l&&tree[x].r<=r){   		tree[x].sum+=v;		tree[x].lazy+=v;		return ;	}	pushdown(x);	int mid=(tree[x].l+tree[x].r)>>1;	if(l<=mid) update(x<<1,l,r,v);	if(mid