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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.  
  24.  
  25. vector<int> a;
  26. void consistency(int n) {
  27.  
  28. 	vector<int> prefixMax(n+1, 0);
  29. 	vector<int> sufixMax(n+1, 0);
  30.  
  31. 	//* Kadane => P[R] = max(P[R-1] + a[R], a[R] , 0 )
  32. 	//* curr = max(prev+a[i], a[i], 0)
  33. 	int prev = 0;
  34. 	int maxi = 0;
  35. 	for(int i=0; i<n; i++){
  36. 		int curr = max(prev+a[i], a[i]);
  37. 		curr = max(curr, 0LL);
  38. 		prev = curr;
  39. 		maxi = max(maxi, curr);
  40. 		prefixMax[i] = maxi;
  41. 	}
  42.  
  43. 	int next = 0;
  44. 	maxi = 0;
  45. 	for(int i=n-1; i>=0; i--){
  46. 		int curr = max(next+a[i], a[i]);
  47. 		curr = max(curr, 0LL);
  48. 		next = curr;
  49. 		maxi = max(maxi, curr);
  50. 		sufixMax[i] = maxi;
  51. 	}
  52.  
  53. 	maxi = 0;
  54. 	for(int i=0; i<n-1; i++){
  55. 		maxi = max(maxi, prefixMax[i] + sufixMax[i+1]);
  56. 	}
  57.  
  58. 	cout << maxi << endl;
  59.  
  60. }
  61.  
  62. void solve() {
  63.  
  64.     int n;
  65.     cin >> n;
  66.     a.resize(n);
  67.     for(int i=0; i<n; i++) cin >> a[i];
  68.     consistency(n) ;
  69.  
  70. }
  71.  
  72.  
  73.  
  74.  
  75.  
  76. int32_t main() {
  77.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  78.  
  79.     int t = 1;
  80.     while (t--) {
  81.         solve();
  82.     }
  83.  
  84.     return 0;
  85. }
Success #stdin #stdout 0s 5320KB
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https://ideone.com/Kcu2O1
language:
C++14 (gcc 8.3)
created:
12 hours ago
visibility:
public

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