prepare (1/3): 
finished

make (2/3): 
g++ -g -Wall -O2 -o p2.o -c p2.cpp 
p2.cpp: In function 'int main()':
p2.cpp:165:10: warning: unused variable 'begin' [-Wunused-variable]
  clock_t begin,end; 
          ^~~~~
p2.cpp:165:16: warning: unused variable 'end' [-Wunused-variable]
  clock_t begin,end; 
                ^~~
p2.cpp: In function 'int partition3(int*, int, int, int)':
p2.cpp:64:6: warning: 'pivotat' may be used uninitialized in this function [-Wmaybe-uninitialized]
  int pivotat;
      ^~~~~~~
g++ -g -Wall -O2 -o main p2.o
finished

clean (3/3): 
finished

all task finished, build successfully