Answer:

def prefix_sum(arr):
    prefix_sum_arr = [0] * len(arr)
    prefix_sum_arr[0] = arr[0]
    for i in range(1, len(arr)):
        prefix_sum_arr[i] = prefix_sum_arr[i - 1] + arr[i]
    return prefix_sum_arr

arr = [10, 20, 10, 5, 15]
result = prefix_sum(arr)
print(result)  # Output: [10, 30, 40, 45, 60]

#leet_codeQ16 #Q_209 #Easy #Prefix_sum
1991. Find the Middle Index in Array

Hint
Given a 0-indexed integer array nums, find the leftmost middleIndex (i.e., the smallest amongst all the possible ones).

A middleIndex is an index where nums[0] + nums[1] + ... + nums[middleIndex-1] == nums[middleIndex+1] + nums[middleIndex+2] + ... + nums[nums.length-1].

If middleIndex == 0, the left side sum is considered to be 0. Similarly, if middleIndex == nums.length - 1, the right side sum is considered to be 0.

Return the leftmost middleIndex that satisfies the condition, or -1 if there is no such index.



Example 1:

Input: nums = [2,3,-1,8,4]
Output: 3
Explanation: The sum of the numbers before index 3 is: 2 + 3 + -1 = 4
The sum of the numbers after index 3 is: 4 = 4
Example 2:

Input: nums = [1,-1,4]
Output: 2
Explanation: The sum of the numbers before index 2 is: 1 + -1 = 0
The sum of the numbers after index 2 is: 0
Example 3:

Input: nums = [2,5]
Output: -1
Explanation: There is no valid middleIndex.


Constraints:

1 <= nums.length <= 100
-1000 <= nums[i] <= 1000

Mean of range in array
#Q17 Geeks for Geeks
Given an array of n integers and q queries. Write a program to find floor value of mean in range l to r for each query in a new line.
Queries are given by an array queries[] of size 2*q. Here queries[2*i] denote l and queries[2*i+1] denote r for i-th query (0<= i <q).

Example 1:

Input : Arr[] = {1, 2, 3, 4, 5}, Q = 3
queries[] = {0, 2, 1, 3, 0, 4}
Output : 2 3 3
Explanation:
Here we can see that the array of
integers is [1, 2, 3, 4, 5].
Query 1: L = 0 and R = 2
Sum = 6
Integer Count = 3
So, Mean is 2
Query 2: L = 1 and R = 3
Sum = 9
Integer Count = 3
So, Mean is 3
Query 3: L = 0 and R = 4
Sum = 15
Integer Count = 5
So, the Mean is 3.
So, In the end, the function will
return the array [2, 3, 3] as an answer.

Example 2:

Input : Arr[] = {6, 7, 8, 10}, Q = 2
queries[] = {0, 3, 1, 2}
Output : 7 7

Try to Solve this problem

#Q18 #leet_codeQ18 Easy
1480 . Given an array nums. We define a running sum of an array as runningSum[i] = sum(nums[0]…nums[i]).

Return the running sum of nums.


Example 1:

Input: nums = [1,2,3,4]
Output: [1,3,6,10]
Explanation: Running sum is obtained as follows: [1, 1+2, 1+2+3, 1+2+3+4].
Example 2:

Input: nums = [1,1,1,1,1]
Output: [1,2,3,4,5]
Explanation: Running sum is obtained as follows: [1, 1+1, 1+1+1, 1+1+1+1, 1+1+1+1+1].
Example 3:

Input: nums = [3,1,2,10,1]
Output: [3,4,6,16,17]


Constraints:

1 <= nums.length <= 1000
-10^6 <= nums[i] <= 10^6

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Code-Forces Question For u

🚀 Problem B: Red and Blue Challenge

🎯 Objective: Help Monocarp restore a sequence from two colored subsequences and maximize the prefix sum.

🔢 Details:
- You have two sequences: Red and Blue.
- Combine them to restore the original sequence that maximizes the prefix sum ( f(a) ).

⏳ Constraints:
- Time Limit: 2 seconds per test
- Memory Limit: 512 MB

📋 Input:
- Number of test cases: t
- For each test case:
- Length of Red sequence (n) and the sequence itself
- Length of Blue sequence (m) and the sequence itself

💡 Example:
Input:

4
4
6 -5 7 -3
3
2 3 -4
2
1 1
4
10 -3 2 2
5
-1 -2 -3 -4 -5
5
-1 -2 -3 -4 -5
1
0
1
0

Output:

13
13
0
0

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🔍 Today’s Topic: Data Structures!

Hey LeetCoders! 🚀 Let’s dive into the world of data structures—the backbone of efficient coding!

💡 What is a Data Structure?

Think of data structures as the organizational tools for your code. They help us store, manage, and manipulate data effectively. Choosing the right data structure can significantly enhance your algorithm's performance!

—

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✨ Challenge of the Day:

Here are 2 common coding interview questions related to data structures:

1. Reverse a Linked List: Given the head of a singly linked list, reverse the list and return the reversed list.
- *Tip*: Think about using pointers!

2. Valid Parentheses: Given a string containing just the characters '(', ')', '', '', '[' and ']', determine if the input string is valid. An input string is valid if:
- Open brackets are closed by the same type of brackets.
- Open brackets are closed in the correct order.

Try solving these problems and share your solutions and thoughts in the chat! Let’s learn together! 💬

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