Category Archives: programming

Find First and Last Position of Element in Sorted Array

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Find first and last position of element in sorted array.

Given a sorted array which contains duplicate elements. Write a code to find first and last position of a number in a sorted array.

OR

Find first and last occurrences of x in sorted array where x is a target value.

If a number is not found return -1.

For example –

Example 1 –

Input : {1, 4, 7, 8, 8, 11, 11, 11, 11, 12, 13, 13} , target = 11

Output: {5, 8}

The first index of 11 is 5 and last index is 8.

Example 2 –

Input: {1, 6, 7, 7, 8, 8, 9, 9},  target = 5

    Output: {-1, -1}

    The target value is not found.

NOTE – We have to solve this problem in O(logn) time complexity.

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PHP Code to Find Second Largest Number in Array

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Write a PHP code to find second largest number in array. Given an unsorted array, we have to write a PHP program to find the second largest number in an array.

Apart from solving this problem. We have to focus on time complexity. As the time complexity of an algorithm is very important in terms of how efficient your algorithm is. →

Binary Search using Recursion in Java

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In this tutorial, I am going to discuss the implementation of a Binary search using recursion in java.

Given an array of sorted integers and a number k. We have to write a code to search  an element k in an array.

For example:

Input: {2, 3, 4, 5, 7, 8},     k = 5

Output: 3 (5 is found at 3rd index)

Input array is sorted and we have to find 5 in this array. The element is found at index 3.

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