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  1. mod=1000000007
  2.  
  3. def add(a,b):
  4.     res=(a+b)%mod
  5.     if(res<0):
  6.         return (res+mod)
  7.     else:
  8.         return res
  9.  
  10. def mul(a,b):
  11.     res=(a*b)%mod
  12.     if(res<0):
  13.         return res+mod
  14.     else:
  15.         return res
  16.  
  17.  
  18. n=int(input())
  19. a=[int(i) for i in input().split()]
  20.  
  21. dp=[]
  22. for i in range(0,1030):
  23.     dp.append([])
  24.     for j in range(0,1030):
  25.         dp[i].append(-mod)
  26.  
  27.  
  28. dp[0][0]=0
  29. dp[0][a[0]]=1
  30.  
  31. for i in range(1,n):
  32.     for j in range(0,1001):
  33.         dp[i][j]=dp[i-1][j]
  34.     for j in range(0,1001):    
  35.         dp[i][a[i]^j]=max(dp[i-1][j]+1,dp[i-1][a[i]^j])
  36.  
  37. l=a[0]
  38. for i in range(1,n):
  39.     if(a[i]>l):
  40.         l=a[i]
  41.  
  42.  
  43. po=[]
  44. po.append(1)
  45. for i in range (1,l+1):
  46.     po.append(mul(po[i-1],31))
  47.  
  48. ans=0
  49. for i in range(0,l+1):
  50.     if(dp[n-1][i]<0):
  51.         dp[n-1][i]=0
  52.     ans=add(ans,mul(dp[n-1][i],po[i]))
  53.  
  54. print(ans)
  55.  
  56.  
Success #stdin #stdout 0.18s 37600KB
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https://ideone.com/QYloPv
language:
Python 3 (python  3.9.5)
created:
6 years ago
visibility:
public

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