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  1.  
  2.  
  3.  
  4. #include <bits/stdc++.h>
  5. using namespace std;
  6.  
  7. //return 1, if == m:
  8. //return 0, if < m:
  9. //return 2, if > m:
  10. int func(int mid, int n, int m) {
  11.     long long ans = 1;
  12.     for (int i = 1; i <= n; i++) {
  13.         ans = ans * mid;
  14.         if (ans > m) return 2;
  15.     }
  16.     if (ans == m) return 1;
  17.     return 0;
  18. }
  19.  
  20. int NthRoot(int n, int m) {
  21.     //Use Binary search on the answer space:
  22.     int low = 1, high = m;
  23.     while (low <= high) {
  24.         int mid = (low + high) / 2;
  25.         int midN = func(mid, n, m);
  26.         if (midN == 1) {
  27.             return mid;
  28.         }
  29.         else if (midN == 0) low = mid + 1;
  30.         else high = mid - 1;
  31.     }
  32.     return -1;
  33. }
  34.  
  35. int main()
  36. {
  37.     int n = 3, m = 27;
  38.     int ans = NthRoot(n, m);
  39.     cout << "The answer is: " << ans << "\n";
  40.     return 0;
  41. }
  42.  
  43.  
Success #stdin #stdout 0s 5284KB
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stdin
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Standard input is empty
stdout
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The answer is: 3
https://ideone.com/FaWlZ0
language:
C++ (gcc 8.3)
created:
12 days ago
visibility:
public

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