BestCoder Round #16

来源：互联网发布：linux 给程序root权限编辑：程序博客网时间：2024/06/05 18:01

1001 Revenge of Segment Tree

这个题目好像很简单的样子，但是我错了好多次

#include <set>#include <map>#include <queue>#include <stack>#include <math.h>#include <string>#include <vector>#include <stdio.h>#include <stdlib.h>#include <iostream>#include <limits.h>#include <string.h>#include <algorithm>#include <functional>using namespace std;#define maxn 447000+5#define mm 1000000007typedef long long ll;ll a[maxn];ll kk[maxn];int main(){    //freopen("in.txt","r",stdin);    //freopen("out.txt","w",stdout);    int t;scanf("%d",&t);    while(t--){        ll n;scanf("%I64d",&n);        for (int i=1;i<=n;i++){            scanf("%I64d",&a[i]);        }        kk[1]=n;kk[n]=n;        for (ll i=2;i<=n/2;i++){            kk[i]=(kk[i-1]+n-2*(i-1))%mm;            kk[n+1-i]=kk[i];        }        if (n%2==1){            kk[n/2+1]=(kk[n/2]+1)%mm;        }        ll ans=0;        for (ll i=1;i<=n;i++){            ans=((ans+((kk[i])%mm*(a[i])%mm))%mm)%mm;        }        printf("%I64d\n",ans);    }    return 0;}

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