What is this error?
==40742== Invalid write of size 4 ==40742== at 0x10929A: split_array (split_array.c:22) ==40742== by 0x1093B3: main (split_array.c:57) ==40742== Address 0x4a730e4 is 0 bytes after a block of size 4 alloc'd ==40742== at 0x483B7F3: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so) ==40742== by 0x109224: split_array (split_array.c:17) ==40742== by 0x1093B3: main (split_array.c:57)
