牛客练习赛29 F 算式子

 

https://www.nowcoder.com/acm/contest/211/F

 

经典题。

1.分区间

2.向下取整的值变化 & 合并相同值

 

 1 #include 
 2 using namespace std;
 3 #define ll long long
 4 const ll mod=1e9+7;
 5 const int maxn=2e6+10;
 6 
 7 ll tot[maxn<<1],f[maxn],g[maxn],add[maxn],ans=0,r;
 8 
 9 int main()
10 {
11     int n,m,a,x,y,i,j;
12     scanf("%d%d",&n,&m);
13     for (i=1;i<=n;i++)
14     {
15         scanf("%d",&a);
16         g[a]++;
17     }
18     for (i=1;i<=m<<1;i++)
19         tot[i]=tot[i-1]+g[i];
20     for (i=1;i<=m;i++)
21         if (g[i])
22         {
23             for (j=i;j<=m;j+=i)
24                 add[j]+=g[i];
25         }
26     for (i=1;i<=m;i++)
27     {
28         for (j=1,x=i-1,y=i+i-1;x<=m;j++,x+=i,y+=i)
29             f[i]+=(tot[y]-tot[x])*j;
30         ans+=add[i];
31         f[i]+=ans;
32     }
33     r=0;
34     for (i=1;i<=m;i++)
35         r=r^f[i];
36     cout<<r;
37     return 0;
38 }
39 /*
40 3 3
41 1 2 3
42 
43 */

 

转载于:https://www.cnblogs.com/cmyg/p/9840435.html