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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define int              long long int
  4. #define double           long double
  5. #define print(a)         for(auto x : a) cout << x << " "; cout << endl
  6.  
  7.  
  8. const int M = 1000000007;
  9. const int N = 3e5+9;
  10. const int INF = 2e9+1;
  11. const int LINF = 2000000000000000001;
  12.  
  13. inline int power(int a, int b, int mod=M) {
  14.     int x = 1;
  15.     a %= mod;
  16.     while (b) {
  17.         if (b & 1) x = (x * a) % mod; 
  18.         a = (a * a) % mod;
  19.         b >>= 1;
  20.     }
  21.     return x;
  22. }
  23.  
  24.  
  25. //_ ***************************** START Below *******************************
  26.  
  27.  
  28.  
  29.  
  30.  
  31. //? Good Subarrays Hashing
  32.  
  33. //* We need to find subarrays : (P[R] - P[L-1])%k == 0
  34. //*                             P[R]%k == P[L-1]%k
  35. //*     Hence for P[R]%k find P[R]%k in past
  36.  
  37.  
  38. //* Eg     :    [4,  5,  0, -2, -3,  1]   , k = 5
  39. //* sum    :  0  4   9   9   7   4   5     
  40. //* sum%m  :  0  4   4   4   2   4   0     
  41. //* ct     :  1  1   2   3   1   4   2
  42. //* ans    :         1 + 2 + 0 + 3 + 1
  43.  
  44.  
  45. vector<int> a;
  46. int consistency(int n, int k) {
  47.  
  48. 	unordered_map<int,int> mp = {{0, 1}};
  49. 	int sum = 0;
  50. 	int ans = 0;
  51. 	for(int i=0; i<n; i++){
  52. 	    sum += a[i];
  53. 	    int rem = ((sum%k)+k)%k;
  54. 	    if(mp.count(rem)){
  55. 	        ans += mp[rem];
  56. 	    }
  57. 	    mp[rem]++;
  58. 	}
  59.  
  60. 	return ans;
  61.  
  62. }
  63.  
  64.  
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  66.  
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  70.  
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  76.  
  77.  
  78.  
  79.  
  80. int practice(int n, int k){
  81.  
  82.  
  83.     return 0;
  84. }
  85.  
  86.  
  87.  
  88.  
  89. void solve() {
  90.  
  91. 	int n, k;
  92. 	cin >> n >> k;
  93.  
  94. 	a.resize(n);
  95. 	for(int i=0; i<n; i++) cin >> a[i];
  96.  
  97.     cout << consistency(n, k) << endl;
  98.  
  99. }
  100.  
  101.  
  102.  
  103.  
  104.  
  105. int32_t main() {
  106.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  107.  
  108.     int t = 1;
  109.     // cin >> t;
  110.     while (t--) {
  111.         solve();
  112.     }
  113.  
  114.     return 0;
  115. }
Success #stdin #stdout 0.01s 5320KB
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5 2
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https://ideone.com/IDngfP
language:
C++14 (gcc 8.3)
created:
22 hours ago
visibility:
public

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