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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. int consistency(int n) {
  27.  
  28. 	vector<int> prefixMaxiDp(n);
  29. 	vector<int> sufixMaxiDp(n);
  30.  
  31. 	int maxi = -INF;
  32. 	int last = 0;
  33. 	for(int i=0; i<n; i++){
  34. 		int curr = max(last + a[i], a[i]);
  35. 		last = curr;
  36. 		maxi = max(maxi, curr);
  37. 		prefixMaxiDp[i] = maxi;
  38. 	}
  39.  
  40. 	last = 0;
  41. 	maxi = -INF;
  42. 	for(int i=n-1; i>=0; i--){
  43. 		int curr = max(last + a[i], a[i]);
  44. 		last = curr;
  45. 		maxi = max(maxi, curr);
  46. 		sufixMaxiDp[i] = maxi;
  47. 	}
  48.  
  49. 	int ans = -INF;
  50. 	for(int i=0; i<n-1; i++){
  51. 		ans = max(ans, prefixMaxiDp[i] + sufixMaxiDp[i+1]);
  52. 	}
  53.  
  54. 	return ans;
  55.  
  56.  
  57. }
  58.  
  59.  
  60.  
  61.  
  62.  
  63.  
  64.  
  65.  
  66.  
  67.  
  68.  
  69.  
  70.  
  71. int practice(int n) {
  72.  
  73. 	vector<int> prefixMax(n);
  74. 	int last = 0;
  75. 	int maxSoFar = -INF;
  76.  
  77. 	for(int i=0; i<n; i++){
  78. 		int curr = max(last+a[i], a[i]);
  79. 		last = curr;
  80. 		maxSoFar = max(maxSoFar, curr);
  81. 		prefixMax[i] = maxSoFar;
  82. 	}
  83.  
  84. 	vector<int> suffixMax(n);
  85. 	last = 0;
  86. 	maxSoFar = -INF;
  87. 	for(int i=n-1; i>=0; i--){
  88. 		int curr = max(last+a[i], a[i]);
  89. 		last = curr;
  90. 		maxSoFar = max(maxSoFar, curr);
  91. 		suffixMax[i] = maxSoFar;
  92. 	}
  93.  
  94. 	int maxi = -INF;
  95. 	for(int i=0; i<n-1; i++){
  96. 		maxi = max(maxi, prefixMax[i] + suffixMax[i+1]);
  97. 	}
  98.  
  99. 	return maxi;
  100.  
  101. }
  102.  
  103.  
  104.  
  105. void solve() {
  106.  
  107. 	int n;
  108. 	cin >> n;
  109. 	a.resize(n);
  110. 	for(int i=0; i<n; i++) cin >> a[i];
  111.     // cout << consistency(n) << endl ;
  112.  
  113.  
  114.     cout << consistency(n) << " -> " << practice(n) << endl;
  115.  
  116. }
  117.  
  118.  
  119.  
  120.  
  121.  
  122. int32_t main() {
  123.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  124.  
  125.     int t = 1;
  126.     while (t--) {
  127.         solve();
  128.     }
  129.  
  130.     return 0;
  131. }
Success #stdin #stdout 0.01s 5316KB
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stdin
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stdout
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18 -> 18
https://ideone.com/PybkGH
language:
C++14 (gcc 8.3)
created:
23 hours ago
visibility:
public

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