SDE - 1

You are given an array of 'N' elements. In this given array, each element appears an even number of times except one element which appears odd no. of times. Your task is to find the element which occurs an odd number of times.

For example :

Input array [5,5,6,4,6],If we look at the frequency of different elements in this array.We can see,4 appears an odd number of times, so our answer will be 4.

You are given a list of ‘N’ words ‘WORDS’. Your task is to return all pairs of the distinct indices (i, j) in ‘WORDS’, such that the concatenation of WORDS[i] and WORDS[j] is a palindrome.

For Example:

You are given ‘WORDS’ = [“cat”, “mat”, “tac”]. Then the answer will be [(0, 2), (2, 0)}, because “cat” + “tac” = “cattac” which is a palindrome and “tac” + “cat” = “taccat” which is also a palindrome.

You have been given a 2-D array 'mat' of size 'M x N' where 'M' and 'N' denote the number of rows and columns, respectively. The elements of each row are sorted in non-decreasing order.

Moreover, the first element of a row is greater than the last element of the previous row (if it exists).

You are given an integer ‘target’, and your task is to find if it exists in the given 'mat' or not.

Example:

Input: ‘M’ = 3, 'N' = 4, ‘mat’ = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]], ‘target’ = 8

Output: true

Explanation: The output should be true as '8' exists in the matrix.

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