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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. inline int power(int a, int b) {
  6.     int x = 1;
  7.     while (b) {
  8.         if (b & 1) x *= a;
  9.         a *= a;
  10.         b >>= 1;
  11.     }
  12.     return x;
  13. }
  14.  
  15.  
  16. const int M = 1000000007;
  17. const int N = 3e5+9;
  18. const int INF = 2e9+1;
  19. const int LINF = 2000000000000000001;
  20.  
  21. //_ ***************************** START Below *******************************
  22.  
  23. // In Good Subarrays problem, draw array && subarray and apply Maths and  find condition
  24.  
  25. //                      L               R
  26. //    [  _  _  _  _  _ (_  _  _  _  _   _) _  _  ]
  27.  
  28.  
  29. //  Given : Px[R] - Px[L-1] == Py[R] - Py[L-1]
  30. //                     cnt of x      ==    cnt of y   in subarray [L,R]
  31. //      Px[R]-Py[R] == Px[L-1] - Py[L-1]
  32. //  Hence find for Px[R] - Py[R] in past 
  33.  
  34.  
  35. vector<int> a;
  36. void consistency(int n) {
  37.  
  38. 	int ones = 0;
  39. 	int zeroes = 0;
  40.  
  41. 	unordered_map<int, int> mp = {{0, -1}};
  42. 	int ans = 0;
  43. 	for(int i=0; i<n; i++){
  44. 		if(a[i] == 0) zeroes++;
  45. 		else ones++;
  46.  
  47. 		if(mp.count(zeroes-ones)){
  48. 			int l = mp[zeroes-ones];
  49. 			int len = i-l;
  50. 			ans = max(ans, len);
  51. 		}
  52. 		if(!mp.count(zeroes-ones)) mp[zeroes-ones] = i;
  53.  
  54. 	}
  55.  
  56. 	cout << ans << endl;
  57. }
  58.  
  59. void solve() {
  60.  
  61.     int n;
  62.     cin >> n;
  63.     a.resize(n);
  64.     for(int i=0; i<n; i++) cin >> a[i];
  65.     consistency(n) ;
  66.  
  67. }
  68.  
  69.  
  70.  
  71.  
  72.  
  73. int32_t main() {
  74.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  75.  
  76.     int t = 1;
  77.     cin >> t;
  78.     while (t--) {
  79.         solve();
  80.     }
  81.  
  82.     return 0;
  83. }
Success #stdin #stdout 0.01s 5320KB
comments (?)
stdin
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4
2
0 1
3
0 1 0
9
0 1 1 1 1 1 0 0 0
8
0 0 1 0 0 0 1 1
stdout
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2
2
6
6
https://ideone.com/J9DylH
language:
C++14 (gcc 8.3)
created:
2 hours ago
visibility:
public

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