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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. string a;
  31.  
  32. bool isPossible(int n, int mid){
  33.  
  34. 	if (mid == 0) return true;
  35.  
  36. 	int P = 31;
  37. 	int MOD = 1e9 + 7;
  38. 	int p_pow = 1;
  39.  
  40. 	for (int i = 0; i < mid - 1; i++) {
  41. 		p_pow = (p_pow * P) % MOD;
  42. 	}
  43.  
  44. 	int s = 0;
  45. 	int e = 0;
  46. 	int hash = 0;
  47.  
  48. 	//* substring -> index
  49. 	unordered_map<int,int> first;
  50. 	unordered_map<int,int> second;
  51.  
  52. 	while(e < n){
  53. 		hash = (hash * P + (a[e] - 'a' + 1)) % MOD;
  54.  
  55. 		if(e - s + 1 < mid){
  56. 			e++;
  57. 		}
  58. 		else{
  59. 			if(!first.count(hash)){
  60. 				first[hash] = s;
  61. 			}
  62. 			else if(!second.count(hash)){
  63. 				if(s >= first[hash] + mid) second[hash] = s;	
  64. 			}
  65. 			else{
  66. 				if(s >= second[hash] + mid) return true;	
  67. 			}
  68.  
  69.  
  70. 			hash = (hash - (a[s] - 'a' + 1) * p_pow) % MOD;
  71. 			if (hash < 0) hash += MOD;
  72.  
  73. 			e++;
  74. 			s++;
  75. 		}
  76. 	}
  77. 	return false;
  78. }
  79.  
  80.  
  81. int consistency(int n){
  82.  
  83. 	int s = 0;
  84. 	int e = n/3+1;
  85.  
  86.  
  87. 	while(s<e){
  88. 		int mid = s + (e-s+1)/2;
  89.  
  90. 		if(isPossible(n, mid)){
  91. 			s = mid;
  92. 		}
  93. 		else{
  94. 			e = mid-1;
  95. 		}
  96.  
  97. 	}
  98.  
  99.  
  100.  
  101. 	return e;
  102. }
  103.  
  104.  
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  108.  
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  110.  
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  117.  
  118.  
  119.  
  120.  
  121.  
  122. void solve() {
  123.  
  124.     cin >> a;
  125.     int n = a.size();
  126.  
  127.     cout << consistency(n) << endl;
  128.  
  129.  
  130. }
  131.  
  132.  
  133.  
  134.  
  135.  
  136. int32_t main() {
  137.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  138.  
  139.     int t = 1;
  140.     // cin >> t;
  141.     while (t--) {
  142.         solve();
  143.     }
  144.  
  145.     return 0;
  146. }
Success #stdin #stdout 0s 5316KB
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https://ideone.com/77LzDg
language:
C++14 (gcc 8.3)
created:
1 day ago
visibility:
public

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