A deep copy copies all fields, and makes copies of dynamically allocated memory pointed to by the fields. A deep copy occurs when an object is copied along with the objects to which it refers.
It makes a copy of all the members of X, allocates different memory location for Y and then assigns the copied members to Y to achieve deep copy. In this way, if X vanishes Y is still valid in the memory.
Original list items before deep copying List 1
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New list of elements after deep copying List 2
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Original elements after deep copying List 1
10 20 30 [40, 50] 60 70