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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. vector<int> a;
  31.  
  32. //* Maintaining Trick : Pivoting k 
  33.  
  34. //* Time = O(n^2)	, Space = O(n)
  35.  
  36. int consistency1(int n){
  37.  
  38. 	int ans = 0;
  39. 	vector<int> pMaxDif(n, 0);
  40.  
  41. 	pMaxDif[1] = a[0] - a[1];
  42.  
  43. 	for(int k=2; k<n; k++){
  44.  
  45. 		int j = k;
  46. 		int i = j-1;
  47. 		int maxDif = pMaxDif[j-1];
  48. 		while(i>=0){
  49. 			maxDif = max(maxDif, a[i] - a[j]);
  50. 			i--;
  51. 		}
  52. 		pMaxDif[j] = maxDif;
  53.  
  54. 		int val = pMaxDif[k-1] * a[k];
  55.  
  56. 		ans = max(ans, val);
  57.  
  58. 	}	
  59.  
  60.  
  61. 	return ans;
  62. }
  63.  
  64.  
  65.  
  66. //* Time = O(n) optimized
  67.  
  68. int consistency2(int n){
  69.  
  70. 	int ans = 0;
  71. 	vector<int> pMaxDif(n, 0);
  72. 	pMaxDif[1] = a[0] - a[1];
  73.  
  74. 	int maxi = max(a[0], a[1]);
  75.  
  76. 	for(int k=2; k<n; k++){
  77.  
  78. 		int j = k;
  79. 		pMaxDif[j] = max(pMaxDif[j-1], maxi - a[j] );
  80. 		maxi = max(maxi, a[j]);
  81.  
  82. 		int val = pMaxDif[k-1] * a[k];
  83.  
  84. 		ans = max(ans, val);
  85.  
  86. 	}	
  87.  
  88.  
  89. 	return ans;
  90. }
  91.  
  92.  
  93.  
  94. //* Time = O(n)  +   Space = O(1)  optimized
  95.  
  96. int consistency3(int n){
  97.  
  98. 	int ans = 0;
  99. 	int maxDifSoFar = a[0] - a[1];
  100.  
  101. 	int maxi = max(a[0], a[1]);
  102.  
  103. 	for(int k=2; k<n; k++){
  104.  
  105. 		int maxDiff = maxDifSoFar;
  106.  
  107. 		maxDifSoFar = max(maxDifSoFar, maxi - a[k] );
  108. 		maxi = max(maxi, a[k]);
  109.  
  110. 		int val = maxDiff * a[k];
  111.  
  112. 		ans = max(ans, val);
  113.  
  114. 	}	
  115.  
  116.  
  117. 	return ans;
  118. }
  119.  
  120.  
  121.  
  122. //* Pivot j : prefix && sufix 
  123.  
  124. int consistency4(int n){
  125.  
  126. 	int ans = 0;
  127. 	vector<int> sufixMaxi(n+1);
  128. 	for(int i=n-1; i>=0; i--){
  129. 		sufixMaxi[i] = max(sufixMaxi[i+1], a[i]);
  130. 	}
  131.  
  132. 	int maxi = a[0];
  133.  
  134. 	for(int j=1; j<=n-2; j++){
  135.  
  136. 		int rightMaxi = sufixMaxi[j+1];
  137.  
  138. 		int val = (maxi - a[j]) * rightMaxi;
  139.  
  140. 		maxi = max(maxi, a[j]);
  141.  
  142. 		ans = max(ans, val);
  143.  
  144. 	}	
  145.  
  146.  
  147. 	return ans;
  148. }
  149.  
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  169.  
  170.  
  171.  
  172.  
  173.  
  174.  
  175.  
  176. int practice(int n){
  177.  
  178.  
  179.     return 0;
  180. }
  181.  
  182.  
  183.  
  184.  
  185.  
  186. void solve() {
  187.  
  188.     int n;
  189.     cin>> n;
  190.  
  191.     a.resize(n);
  192.     for(int i=0; i<n; i++) cin >> a[i];
  193.  
  194.     cout << consistency1(n) << " " << consistency2(n) << " " << consistency3(n) << " " << consistency4(n) << endl;
  195.  
  196.  
  197. }
  198.  
  199.  
  200.  
  201.  
  202.  
  203. int32_t main() {
  204.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  205.  
  206.     int t = 1;
  207.     // cin >> t;
  208.     while (t--) {
  209.         solve();
  210.     }
  211.  
  212.     return 0;
  213. }
Success #stdin #stdout 0.01s 5276KB
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https://ideone.com/craQ1F
language:
C++14 (gcc 8.3)
created:
1 day ago
visibility:
public

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