It has been adjust to work only with int arrays and perform operation on worst case scenario for merge sort, which is something similar to this array - [0, 2, 4, 6, 1, 3, 5, 7].
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<b>CODE</b>
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To compile on matrix - <b>g++ -O2 -g -pg -oa1 a1.cpp</b>
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<b>Profiling</b>
==================Profiling with 1000000 elements <source>Flat profile: Each sample counts as 0.01 seconds. % cumulative self self total time seconds seconds calls ms/call ms/call name 69.23 0.09 0.09 999999 0.00 0.00 merge(int*, int*, int, int, int) 30.77 0.13 0.04 1 40.00 130.00 mSort(int*, int*, int, int) 0.00 0.13 0.00 1 0.00 0.00 _GLOBAL__sub_I_SIZE </source> Profiling with 10000000 elements <source>Flat profile: Each sample counts as 0.01 seconds. % cumulative self self total time seconds seconds calls s/call s/call name 88.89 1.04 1.04 9999999 0.00 0.00 merge(int*, int*, int, int, int) 11.11 1.17 0.13 1 0.13 1.17 mSort(int*, int*, int, int) 0.00 1.17 0.00 1 0.00 0.00 _GLOBAL__sub_I_SIZE </source> Profiling with 100000000 elements
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<b>Analysing</b>
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The most time consuming part is merging, which can be at least partially paralleled. The Big(O) of this case is O(n).
