codeforces772C

给一段序列，给你去掉所有数字的顺序，输出每去掉一个数，当前联通的子序列的最大值。

倒着来，每次插入一个数，然后求联通的最大值，线段树每个节点标记一下，区间的左右是否插入了数字，还有如果有数字从左边/右边开始连续子序列的值，还有这个节点的区间是否连续。

 #include <cstdio>

 #include <algorithm>

 using namespace std;

 typedef long long LL;

 const int maxn=;

 int n;

 int i;

 int a[maxn+];

 int b[maxn+];

 LL res[maxn+];

 struct node{
     int l,r;
     LL sum;
     int lflag,rflag;
     LL lval,rval;
     bool f;
 }tree[maxn*+];

 void push_up(int id){
    int llf=tree[id<<].lflag;
    int lrf=tree[id<<].rflag;
    int rlf=tree[(id<<)+].lflag;
    int rrf=tree[(id<<)+].rflag;
    if(lrf&&rlf){
       tree[id].sum=max(max(tree[id<<].rval+tree[(id<<)+].lval,tree[id<<].sum),tree[(id<<)+].sum);
       tree[id].lflag=llf;
       tree[id].rflag=rrf;
       if(llf){
       if(tree[id<<].f)
       tree[id].lval=tree[id<<].lval+tree[(id<<)+].lval;
       else tree[id].lval=tree[id<<].lval;
       } else {
           tree[id].lval=;
       }
       if(rrf){
       if(tree[(id<<)+].f){
       tree[id].rval=tree[(id<<)].rval+tree[(id<<)+].rval;
       }
       else tree[id].rval=tree[(id<<)+].rval;
       } else {
          tree[id].rval=;
       }
       tree[id].f=tree[(id<<)].f&&tree[(id<<)+].f;
    }else if(!lrf||!rlf){
       if(tree[id<<].sum>tree[(id<<)+].sum){
             tree[id].sum=tree[id<<].sum;
             tree[id].lflag=llf;
             tree[id].rflag=rrf;
             if(!llf)
             tree[id].lval=;
             else tree[id].lval=tree[id<<].lval;
             if(!rrf)
             tree[id].rval=;
             else
             tree[id].rval=tree[(id<<)+].rval;
             tree[id].f=;
       } else if(tree[id<<].sum<tree[(id<<)+].sum){
              tree[id].sum=tree[(id<<)+].sum;
              tree[id].lflag=llf;
              tree[id].rflag=rrf;
              if(!llf)
              tree[id].lval=;
              else tree[id].lval=tree[id<<].lval;
              if(!rrf)
              tree[id].rval=;
              else
              tree[id].rval=tree[(id<<)+].rval;
              tree[id].f=;
       } else if(tree[id<<].sum==tree[(id<<)+].sum){
              tree[id].sum=tree[id<<].sum;
              tree[id].lflag=llf;
              tree[id].rflag=rrf;
              if(!llf)
              tree[id].lval=;
              else tree[id].lval=tree[id<<].lval;
              if(!rrf)
              tree[id].rval=;
              else
              tree[id].rval=tree[(id<<)+].rval;
              tree[id].f=;
       }

    }
 }

 void build(int id,int l,int r){
      if(l==r){
        tree[id].l=tree[id].r=l;
        tree[id].sum=;
        tree[id].lflag=tree[id].rflag=;
        tree[id].lval=tree[id].rval=;
        tree[id].f=;
        return ;
      }
      int mid=(l+r)>>;
      build(id<<,l,mid);
      build((id<<)+,mid+,r);
      push_up(id);
 }

 void update(int id,int l,int r,int x,int val){
         if(l==r){
         tree[id].sum+=(LL)val;
         tree[id].lflag=tree[id].rflag=;
         tree[id].lval=tree[id].rval=val;
         tree[id].f=;
         return ;
      }
      int mid=(l+r)>>;
      if(x<=mid){
        update(id<<,l,mid,x,val);
      } else {
        update((id<<)+,mid+,r,x,val);
      }
      push_up(id);
 }

 int main()
 {
     scanf("%d",&n);
     build(,,n);
     for(i=;i<=n;i++){
         scanf("%d",&a[i]);
     }
     for(i=;i<=n;i++){
         scanf("%d",&b[i]);
     }
     for(i=n;i>=;i--){
           update(,,n,b[i],a[b[i]]);
           res[i]=tree[].sum;
     }
     for(int i=;i<=n+;i++){
        printf("%I64d\n",res[i]);
     }
     return ;
 }