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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int ternarySearch(int l, int r, int key, vector<int> ar)
  5. {
  6.     if (r >= l) {
  7.         int mid1 = l + (r - l) / 3;
  8.         int mid2 = r - (r - l) / 3;
  9.         if (ar[mid1] == key) {
  10.             return mid1;
  11.         }
  12.         if (ar[mid2] == key) {
  13.             return mid2;
  14.         }
  15.         if (key < ar[mid1]) {
  16.             return ternarySearch(l, mid1 - 1, key, ar);
  17.         }
  18.         else if (key > ar[mid2]) {
  19.             return ternarySearch(mid2 + 1, r, key, ar);
  20.         }
  21.         else {
  22.             return ternarySearch(mid1 + 1, mid2 - 1, key, ar);
  23.         }
  24.     }
  25.     return -1;
  26. }
  27. int main()
  28. {
  29.     int n; cin >> n;
  30.     vector<int> a(n);
  31.     for(int i=0; i<n; i++){
  32.         cin >> a[i];
  33.     }
  34.     cout << ternarySearch(0, n-1, 5, a);
  35. }
  36.  
Success #stdin #stdout 0.01s 5288KB
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stdin
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stdout
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https://ideone.com/0LocP4
language:
C++14 (gcc 8.3)
created:
13 days ago
visibility:
public

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