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  1. // em thu thoi
  2. #include <bits/stdc++.h>
  3.  
  4. using namespace std;
  5.  
  6. #define int long long
  7. #define ld long double
  8. #define eb emplace_back
  9. #define pb push_back
  10. #define fi first
  11. #define se second
  12. #define nn '\n'
  13. #define pi pair<int, int>
  14. #define unmp unordered_map
  15. #define uns unordered_set
  16. #define lb lower_bound
  17. #define ub upper_bound
  18. #define TASK " "
  19.  
  20. #define FOR(i, a, n) for(int  i =  (a) ; i <= (n) ; i++ )
  21. #define FORD(i, a, n) for(int i = (a); i >= (n); i--)
  22. #define FORX(i, x) for(auto (i) : (x))
  23. #define ms(a, x) memset((a), (x), sizeof((a)))
  24. #define all(a) (a).begin(), (a).end()
  25. #define All(a, n) (a) + 1, (a) + 1 + n
  26.  
  27.  
  28. const int INF = 1e18;
  29. const int mod = 1e9+7;
  30. const int N = 1e6 + 5;
  31. int n;
  32. char a[N];
  33. map<char, int> cnt;
  34. int mx = 0;
  35. int mn = INF;
  36. int kq = 0;
  37. vector<int> pos[26];
  38. void nhap(){
  39.     cin >> n;
  40.     FOR(i, 1, n){
  41.     	cin >> a[i];
  42.     	pos[a[i] - 'a'].pb(i);
  43.     }
  44. }
  45. void solve(){
  46. 	 for(int i = 0; i <= 25; i++){
  47. 	 	if(pos[i].empty()) continue;
  48. 	 	for(int j = 0; j <= 25; j++){
  49. 	 		// gia su i la max, j la min
  50. 	 		if(i == j || pos[j].empty()) continue;
  51. 	 		int cnti = 0, cntj = -1000000000;
  52. 	 		int u = 0, v = 0;
  53. 	 		while(u < (int)pos[i].size() || v < (int)pos[j].size()){
  54. 	 			if(u < (int)pos[i].size() && (v == (int)pos[j].size() || pos[i][u] < pos[j][v])){
  55. 	 				cnti++; 
  56. 	 				if(cntj != -1000000000){
  57. 	 					cntj++;
  58. 	 				}
  59. 	 				u++;
  60. 	 			} 
  61.  
  62. 	 			else{
  63. 	 				cntj = max(cnti - 1, (cntj != -1000000000 ? cntj - 1 : -1000000000));
  64. 	 				cnti = 0;
  65. 	 				v++;
  66. 	 			} 
  67.  
  68. 	 			if(cntj != -1000000000){
  69. 	 				kq = max(kq, cntj);
  70. 	 			}
  71. 	 		}
  72.  
  73. 	 	}
  74. 	 }
  75. 	 cout << kq << nn;
  76. }
  77. signed main() {
  78. 	//freopen("CSBN.INP", "r", stdin);
  79. 	//freopen("CSBN.OUT", "w", stdout);
  80. 	ios_base::sync_with_stdio(0);
  81. 	cin.tie(0);
  82. 	cout.tie(0);
  83. 	nhap();
  84. 	solve();
  85.     return 0;
  86. }
Success #stdin #stdout 0.01s 5308KB
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https://ideone.com/F89gr9
language:
C++14 (gcc 8.3)
created:
16 hours ago
visibility:
public

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