WT-Pravesh Sakhare.pptx
- 1. Name-Pravesh Sakhare Roll No-49 Subject-Web Technology Branch-CsE(Cyber sEcUriTy) Topic-Javascript Recursion And here your subtitle.
- 2. Recursive Functions • Recursive functions are functions that call themselves. • Data structures, especially linked implementations of binary trees, sometimes use recursive functions Example: Factorial Function • The factorial function is often written as a recursive function. • The factorial of a positive integer is the product of all positive integers less than or equal to the number. 5 factorial is written 5! 5! = 5 * 4 * 3 * 2 * 1 = 120 3! = 3 * 2 * 1 = 6 0! is defined to be
- 3. Recursive Process (cont.) x = factorial( 4 ); int factorial( int num ) { if ( num == 0 || num == 1 ) 4 replaces each occurrence of num Recursive Process return 1; return num * factorial( num – 1 ); }
- 4. Base Case 1 int factorial( int num ) 2 { 3 if ( num == 0 || num == 1 ) 4 return 1; 5 return num * factorial( num – 1 ); 6 } Notice that these lines stopped the recursion – without these lines, the function will call itself over and over again (infinite recursion
- 5. Infinite Recursion 1 int factorial( int num ) 2 { 3 if ( num == 0 || num == 1 ) 4 return 1; 5 return num * factorial( num – 1 ); 6 } If one makes a mistake and inputs a negative number into this function: factorial( -2 ); what will happen? Infinite recursion
- 6. Guidelines • There must be a base case that stops recursion. • Each recursive call should approach the base case. • The recursive function call should work for the base case. • The recursive function call should work for the case next to the base case. • The recursive function should make logical sense, assuming that the recursive function call inside it does everything it should do
- 7. Recursion on a Linked List (cont.) bool search( Node *ptr, T& foundItem, T& target) { .if ( ptr == NULL ) return false; if ( ptr->info == target ) { foundItem = ptr->info; return true; } return search( ptr->next, foundItem, target ); } Searching for a Mercedes in the linked list: Car mercedes, foundCar; … bool found = search( start, foundCar, mercedes );
- 8. Thank You