Mastering Development in Python : Assignment 3 | Python- Mastering Development in Python - Software Development PDF Download

Q1: Given an array of strings words, return the first palindromic string in the array. If there is no such string, return an empty string "".

A string is palindromic if it reads the same forward and backward.

Example 1:

Input: words = ["abc","car","ada","racecar","cool"]

Output: "ada"

Explanation: The first string that is palindromic is "ada".

Note that "racecar" is also palindromic, but it is not the first.

Example 2:

Input: words = ["notapalindrome","racecar"]

Output: "racecar"

Explanation: The first and only string that is palindromic is "racecar".

Example 3:

Input: words = ["def","ghi"]

Output: ""

Explanation: There are no palindromic strings, so the empty string is returned.

 Constraints:

1 <= words.length <= 100

1 <= words[i].length <= 100

words[i] consists only of lowercase English letters.

Ans:  

Q2:  You are given a string s consisting of lowercase English letters, and you are allowed to perform operations on it. In one operation, you can replace a character in s with another lowercase English letter.

Your task is to make s a palindrome with the minimum number of operations possible. If there are multiple palindromes that can be made using the minimum number of operations, make the lexicographically smallest one.

A string a is lexicographically smaller than a string b (of the same length) if in the first position where a and b differ, string a has a letter that appears earlier in the alphabet than the corresponding letter in b.

Return the resulting palindrome string.

Example 1:

Input: s = "egcfe"

Output: "efcfe"

Explanation: The minimum number of operations to make "egcfe" a palindrome is 1, and the lexicographically smallest palindrome string we can get by modifying one character is "efcfe", by changing 'g'.

Example 2:

Input: s = "abcd"

Output: "abba"

Explanation: The minimum number of operations to make "abcd" a palindrome is 2, and the lexicographically smallest palindrome string we can get by modifying two characters is "abba".

Example 3:

Input: s = "seven"

Output: "neven"

Explanation: The minimum number of operations to make "seven" a palindrome is 1, and the lexicographically smallest palindrome string we can get by modifying one character is "neven".

 Constraints:

1 <= s.length <= 1000

s consists of only lowercase English letters.

Ans: 

Q3:

You are given two strings word1 and word2. Merge the strings by adding letters in alternating order, starting with word1. If a string is longer than the other, append the additional letters onto the end of the merged string.

Return the merged string.

Example 1:

Input: word1 = "abc", word2 = "pqr"

Output: "apbqcr"

Explanation: The merged string will be merged as so:

word1:  a   b   c

word2:    p   q   r

merged: a p b q c r

Example 2:

Input: word1 = "ab", word2 = "pqrs"

Output: "apbqrs"

Explanation: Notice that as word2 is longer, "rs" is appended to the end.

word1:  a   b 

word2:    p   q   r   s

merged: a p b q   r   s

Example 3:

Input: word1 = "abcd", word2 = "pq"

Output: "apbqcd"

Explanation: Notice that as word1 is longer, "cd" is appended to the end.

word1:  a   b   c   d

word2:    p   q 

merged: a p b q c   d

Constraints:

1 <= word1.length, word2.length <= 100

word1 and word2 consist of lowercase English letters.

Ans: 

Q4: 

Given an integer array nums sorted in non-decreasing order, return an array of the squares of each number sorted in non-decreasing order.

Example 1:

Input: nums = [-4,-1,0,3,10]

Output: [0,1,9,16,100]

Explanation: After squaring, the array becomes [16,1,0,9,100].

After sorting, it becomes [0,1,9,16,100].

Example 2:

Input: nums = [-7,-3,2,3,11]

Output: [4,9,9,49,121]

 Constraints:

1 <= nums.length <= 104

-104 <= nums[i] <= 104

nums is sorted in non-decreasing order.

Ans: 

Q5:  Given an array of integers nums, half of the integers in nums are odd, and the other half are even.

Sort the array so that whenever nums[i] is odd, i is odd, and whenever nums[i] is even, i is even.

Return any answer array that satisfies this condition.

Example 1:

Input: nums = [4,2,5,7]

Output: [4,5,2,7]

Explanation: [4,7,2,5], [2,5,4,7], [2,7,4,5] would also have been accepted.

Example 2:

Input: nums = [2,3]

Output: [2,3]

 Constraints:

2 <= nums.length <= 2 * 104

nums.length is even.

Half of the integers in nums are even.

0 <= nums[i] <= 1000

Ans: