2017多校训练Contest2: 1003 Maximum Sequence hdu6047

Problem Description

Steph is extremely obsessed with “sequence problems” that are usually seen on magazines: Given the sequence 11, 23, 30, 35, what is the next number? Steph always finds them too easy for such a genius like himself until one day Klay comes up with a problem and ask him about it.

Given two integer sequences {ai} and {bi} with the same length n, you are to find the next n numbers of {ai}: an+1…a2n. Just like always, there are some restrictions on an+1…a2n: for each number ai, you must choose a number bk from {bi}, and it must satisfy ai≤max{aj-j│bk≤j<i}, and any bk can’t be chosen more than once. Apparently, there are a great many possibilities, so you are required to find max{∑2nn+1ai} modulo 109+7 .

Now Steph finds it too hard to solve the problem, please help him.

 

Input

The input contains no more than 20 test cases.
For each test case, the first line consists of one integer n. The next line consists of n integers representing {ai}. And the third line consists of n integers representing {bi}.
1≤n≤250000, n≤a_i≤1500000, 1≤b_i≤n.

 

Output

For each test case, print the answer on one line: max{∑2nn+1ai} modulo 109+7。

 

Sample Input

48 11 8 53 1 4 2

按照题意把bi-i压入堆中，每次取最大的即可

#include<queue>#include<vector>#include<cstdio>#include<string>#include<cstring>#include<cassert>#include<iostream>#include<algorithm>using namespace std;long long mod=1000000007;long long a[250001];int b[250001];priority_queue<pair<long long,int>> Q;int main(){    int n;    while(scanf("%d",&n)!=EOF)    {        int i;        while(!Q.empty())            Q.pop();        for(i=1;i<=n;i++)        {            scanf("%lld",&a[i]);            Q.push(make_pair(a[i]-i,i));        }        for(i=1;i<=n;i++)            scanf("%d",&b[i]);        sort(b+1,b+1+n);        long long ans=0;        for(i=1;i<=n;i++)        {            pair<long long,int> d;            d=Q.top();        //    Q.pop();            while(d.second<b[i])            {                Q.pop();                d=Q.top();            }            ans+=d.first;            ans%=mod;            d.first-=(i+n);            d.second=i+n;            Q.push(d);        }        ans=(ans+mod)%mod;        printf("%lld\n",ans);    }    return 0;}