【HDU】6047

题目链接：点击打开题目

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跟队友商量了一下，感觉前面的数越大，结果就越优，那么我们就把b排一下序，然后跑一遍就行啦。

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代码如下：

#include<cstdio>#include<vector>#include<algorithm>using namespace std;#define INF 0x3f3f3f3fint a[250000+5];int maxx[250000+5];vector<int> b;const int MOD = 1e9 + 7;int main(){    int n;    int ans;    while (~scanf ("%d",&n))    {        ans = 0;        for (int i = 1 ; i <= n ; i++)            scanf ("%d",&a[i]);        b.clear();        b.resize(n);        for (int i = 0 ; i < n ; i++)            scanf ("%d",&b[i]);        maxx[n] = a[n]-n;        for (int i = n-1 ; i >= 1 ; i--)            maxx[i] = max(maxx[i+1],a[i]-i);        sort(b.begin(),b.end());        int t = -INF;       //后面数的最大值         for (int i = 0 ; i < n ; i++)        {            int num = max(maxx[b[i]],t);            t = max(t,num-(n+i+1));            ans = (ans + num) % MOD;        }        printf ("%d\n",ans);    }    return 0;}