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  1. #include <bits/stdc++.h> 
  2.  
  3. using namespace std;  
  4.  
  5. typedef long long ll;  
  6. typedef pair<int, int> ii;  
  7.  
  8. const int INF = 1e9;  
  9. const ll LINF = 1e18;  
  10.  
  11. struct BigInt {	
  12. 	static const int BASE = 1e9; 
  13. 	static const int B = 9; 
  14.  
  15. 	vector<int> a; 
  16.  
  17. 	BigInt() {}
  18.  
  19. 	BigInt(ll x) {
  20. 		for (; x > 0; x /= BASE) {
  21. 			a.push_back(x % BASE); 
  22. 		}
  23. 	}
  24.  
  25. 	BigInt(const string &s) {
  26. 		for (int i = (int)s.size() - 1; i >= 0; i -= B) {
  27. 			int beg = max(0, i - B + 1); 
  28. 			int len = i - beg + 1;  
  29. 			int block = stoi(s.substr(beg, len)); 
  30. 			a.push_back(block); 
  31. 		}	
  32. 		trim();
  33. 	}
  34.  
  35. 	void trim() {
  36. 		while (!a.empty() && a.back() == 0) {
  37. 			a.pop_back(); 
  38. 		}
  39. 	}
  40.  
  41. 	bool isZero() {
  42. 		return (a.empty()); 
  43. 	}
  44.  
  45. 	BigInt operator*=(const BigInt &other) {
  46. 		int n = a.size(), m = other.a.size();
  47. 		vector<int> c(n + m, 0);  
  48. 		for (int i = 0; i < n; i++) {
  49. 			int carry = 0;  
  50. 			for (int j = 0; j < m || carry; j++) {
  51. 				ll cur = c[i + j] + 1ll * a[i] * (j < m ? other.a[j] : 0) + carry;   
  52. 				c[i + j] = cur % BASE; 
  53. 				carry = cur / BASE; 
  54. 			}
  55. 		}
  56. 		swap(a, c); 
  57. 		trim();
  58. 		return *this; 
  59. 	}
  60.  
  61. 	BigInt operator*(const BigInt &other) const {
  62. 		return BigInt(*this) *= other; 
  63. 	}
  64.  
  65. 	friend istream& operator>>(istream &in, BigInt &num) {
  66. 		string s;
  67. 		in >> s; 	
  68. 		num = BigInt(s);  
  69. 		return in; 
  70. 	}
  71.  
  72. 	friend ostream& operator<<(ostream &out, const BigInt &num) {
  73. 		out << (num.a.empty() ? 0 : num.a.back()); 
  74. 		for (int i = (int)num.a.size() - 2; i >= 0; i--) {
  75. 			out << setw(B) << setfill('0') << num.a[i]; 
  76. 		}
  77. 		return out; 
  78. 	}
  79. }; 
  80.  
  81. int main() {
  82. 	ios::sync_with_stdio(false); 
  83. 	cin.tie(nullptr); 	
  84. 	int t; cin >> t; 
  85.  
  86. 	while (t--) {
  87. 		BigInt a, b; 
  88. 		cin >> a >> b;   
  89. 		cout << a * b << '\n'; 
  90. 	}
  91. }
Success #stdin #stdout 0.01s 5284KB
comments (?)
stdin 
5
4 2
123 43
324 342
0 12
9999 12345
stdout 
8
5289
110808
0
123437655
https://ideone.com/Xf7cd5
language:
C++14 (gcc 8.3)
created:
192 days ago
visibility:
secret

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