How to rotate a N x N matrix by 90 degrees? [closed]

by 
for(int i=0; i<n/2; i++)
   for(int j=0; j<(n+1)/2; j++)
       cyclic_roll(m[i][j], m[n-1-j][i], m[n-1-i][n-1-j], m[j][n-1-i]);


void cyclic_roll(int &a, int &b, int &c, int &d)
{
   int temp = a;
   a = b;
   b = c;
   c = d;
   d = temp;
}

Note I haven’t tested this, just compoosed now on the spot. Please test before doing anything with it.

More Related Contents:

  1. find the number of times a character occurs between two indexes
  2. Program to find sum of prime numbers between 1 and 10^7
  3. banker’s algorithm in c++
  4. Algorithm (especially for c++) to show Every Permutation
  5. Random generation of numbers? [closed]
  6. Which is the fastest algorithm to find prime numbers?
  7. Sorting zipped (locked) containers in C++ using boost or the STL
  8. What is the fastest way to transpose a matrix in C++?
  9. Rounding up to the nearest multiple of a number
  10. Why will std::sort crash if the comparison function is not as operator
  11. Magic number in boost::hash_combine
  12. Creating all possible k combinations of n items in C++
  13. Finding all the subsets of a set
  14. How do I calculate the week number given a date?
  15. Efficient implementation of log2(__m256d) in AVX2
  16. Where can I get a “useful” C++ binary search algorithm?
  17. C++ string::find complexity
  18. C++: Converting Hexadecimal to Decimal
  19. Printing prime numbers from 1 through 100
  20. Circular lock-free buffer
  21. Generating m distinct random numbers in the range [0..n-1]
  22. Fastest algorithm for primality test [closed]
  23. Efficiently getting all divisors of a given number
  24. Ways to do modulo multiplication with primitive types
  25. Removing ‘#include ‘ doesn’t break the code
  26. Is it possible to map string to int faster than using hashmap?
  27. Is it possible to implement lock free map in C++
  28. stl ordering – strict weak ordering
  29. Calculate mean and standard deviation from a vector of samples in C++ using Boost
  30. Checking if all elements of a vector are equal in C++

Leave a Comment