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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. #define NMAX 		100009
  5. #define DEBUG(x) 	cout << '>' << #x << ':' << x << endl;
  6.  
  7. typedef long long int i64;
  8. const int mod = 1000000007 ;
  9.  
  10. int main(void)
  11. {
  12. 	//freopen("in.txt","r",stdin);
  13. 	string inp ;
  14. 	cin>>inp ;
  15. 	int n = inp.size() , i ;
  16. 	char arr[n] ;
  17. 	for(i=0;i<n;i++){
  18.         arr[i] = inp[n-i-1] ;
  19. 	}
  20. 	i64 no_b = 0 , ans = 0 ;
  21. 	for(i=0;i<n;i++){
  22.         if(arr[i]=='a'){
  23.             ans = (ans%mod + no_b%mod)%mod ;
  24.             no_b += no_b ;
  25.             ans %= mod ;
  26.         }
  27.         else{
  28.             no_b++ ;
  29.         }
  30. 	}
  31. 	cout<<ans<<endl;
  32. 	return 0;
  33. }
  34.  
Success #stdin #stdout 0s 15224KB
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stdin 
Standard input is empty
stdout 
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https://ideone.com/UY2in5
language:
C++ (gcc 8.3)
created:
7 years ago
visibility:
secret

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