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  1. #include<iostream>
  2. using namespace std;
  3.  
  4. #define MOD 1000000007
  5.  
  6. long long a[1000000];
  7. long long c[1000000];
  8. long long dist[100000000];
  9. long long sum;
  10. int n, q;
  11.  
  12. long long power(int a, int b) {
  13. 	long long res = 1;
  14. 	for (int j = 1; j <= b; j++) {
  15. 		res *= a;
  16. 		res %= MOD;
  17. 	}
  18. 	return res;
  19. }
  20.  
  21. int main() {
  22. 	cin >> n >> q;
  23. 	for (int i = 1; i <= n; i++) {
  24. 		cin >> a[i];
  25. 	}
  26. 	c[0] = 1;
  27. 	c[q + 1] = 1;
  28. 	for (int i = 1; i <= q; i++) {
  29. 		cin >> c[i];
  30. 	}
  31. 	for (int i = 2; i <= n; i++) {
  32. 		dist[i] = power(a[i - 1], a[i]);
  33. 	}
  34. 	for (int i = 1; i <= q + 1; i++) {
  35. 		if (c[i - 1] < c[i]) {
  36. 			for (int j = c[i - 1] + 1; j <= c[i]; j++) {
  37. 				sum += dist[j];
  38. 				sum %= MOD;
  39. 			}
  40. 		}
  41. 		else {
  42. 			for (int j = c[i - 1]; j >= c[i] + 1; j--) {
  43. 				sum += dist[j];
  44. 				sum %= MOD;
  45. 			}
  46. 		}
  47. 	}
  48. 	cout << sum << endl;
  49. 	return 0;
  50. }
Success #stdin #stdout 0s 800256KB
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876796540
https://ideone.com/T0eqly
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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