I. Recursion
1. Basic concepts
In simple terms, recursion means that the method calls itself, passing in a different variable each time. Recursion helps programmers solve complex problems while keeping code simple
2. Call mechanism
Use an example to illustrate the recursive invocation mechanism
3. Problems solved
- Various math problems: 8 queens, Hannott’s Tower, factorial problem, maze problem, ball and basket problem
- Recursion is also used in various algorithms, such as quicksort, binary search, divide-and-conquer, etc
- Problems that need to be solved with stacks
4. Rules to follow
- When a method is executed, a new protected independent space (stack space) is created
- The local variables of a method are independent and do not affect each other, such as the n variable; If a method uses a variable of a reference type (such as an array), the data of that reference type is shared.
- The recursion must approach the condition for quitting recursion, otherwise it will be infinite recursion, causing stack overflow
- When a method completes execution, it returns (if there is a return value, just as the result of execution is returned to the caller)