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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3. #define sz(s) long(s.size())
  4. #define ll long long
  5. #define F first
  6. #define S second
  7. #define pb push_back
  8. #define all(v) v.begin(), v.end()
  9. #define file(s) freopen(s".in", "r", stdin); freopen(s".out", "w", stdout)
  10. const int N=1e6+2, mod=1e9+7;
  11. char a[N];
  12. vector<vector<int> > g(28);
  13. int n;
  14. signed main() {
  15. 	string s;
  16. 	cin>>s;
  17. 	n=sz(s);
  18. 	for(int i=1; i<=n; i++)a[i]=s[i-1];
  19. 	for(int i=1; i<=n; i++) {
  20. 		g[int(a[i]-'A')].pb(i);
  21. 	}
  22. 	ll cnt=0;
  23. 	for(int i=1; i<=n; i++) {
  24. 		for(int j=0; j<=27; j++) {
  25. 			if(g[j].empty() || g[j].back()<i)continue;
  26. 			if(sz(g[j])==1) {
  27. 				if(g[j][0]>=i)cnt=(cnt+(n-g[j][0]+1))%mod;
  28. 				continue;
  29. 			}
  30. 			int l=0, r=sz(g[j])-1;
  31. 			while(l<=r) {
  32. 				int mid=(l+r)>>1;
  33. 				if(g[j][mid]>=i)r=mid-1;
  34. 				else l=mid+1;
  35. 			}
  36. 			if(l==sz(g[j])-1) {
  37. 				cnt=(cnt+(n-g[j][l]+1))%mod;
  38. 				continue;
  39. 			}
  40. 			cnt=(cnt+(g[j][l+1]-g[j][l]))%mod;
  41. 		}
  42. 	}
  43. 	cout << cnt%mod << '\n';
  44. }
Success #stdin #stdout 0.01s 5476KB
comments (?)
stdin 
ABC
stdout 
10
https://ideone.com/0gTB6A
language:
C++14 (gcc 8.3)
created:
2 years ago
visibility:
secret

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