Hướng dẫn recursive search in python

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Given an unsorted array and an element x, search x in the given array. Write recursive C code for this. If the element is not present, return -1. 

Approach : The idea is to compare x with the last element in arr[]. If the element is found at the last position, return it. Else recur searchElement() for remaining array and element x. 

C++

#include

using namespace std;

int searchElement(int arr[], int size, int x) {

    size--;

    if (size < 0) {

        return -1;

    }

    if (arr[size] == x) {

        return size;

    }

    return searchElement(arr, size, x);

}

int main() {

    int arr[] = {17, 15, 11, 8, 13, 19};

    int size = sizeof(arr) / sizeof(arr[0]);

    int x = 11;

    int idx = searchElement(arr, size, x);

    if (idx != -1) 

        cout << "Element " << x << " is present at index " <

    else 

        cout << "Element " << x << " is not present in the array";

    return 0;

}

C

#include

int elmntSrch(int arr[], int size, int x) {

    int rec;

    size--;

    if (size >= 0) {

        if (arr[size] == x)

            return size;

        else

            rec = elmntSrch(arr, size, x);

    }

    else

        return -1;

    return rec;

}

int main(void) {

    int arr[] = {12, 34, 54, 2, 3};

    int size = sizeof(arr) / sizeof(arr[0]);

    int x = 3;

    int indx;

    indx = elmntSrch(arr, size, x);

    if (indx != -1)

        printf("Element %d is present at index %d", x, indx);

    else

        printf("Element %d is not present", x);

    return 0;

}

Java

class Test

{

     static int arr[] = {12, 34, 54, 2, 3};

     static int recSearch(int arr[], int l, int r, int x)

     {

          if (r < l)

             return -1;

          if (arr[l] == x)

             return l;

          if (arr[r] == x)

             return r;

          return recSearch(arr, l+1, r-1, x);

     }

     public static void main(String[] args) 

     {

        int x = 3; 

        int index = recSearch(arr, 0, arr.length-1, x);

        if (index != -1)

           System.out.println("Element " + x + " is present at index " + 

                                                    index);

        else

            System.out.println("Element " + x + " is not present");

        }

 }

Python3

def recSearch( arr, l, r, x):

    if r < l:

        return -1

    if arr[l] == x:

        return l

Element 11 is present at index 2