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Given a list of numbers, the task is to find and return a list with the cumulative sum of given list.
Examples :
Input: list = [10, 20, 30, 40, 50]
Output : [10, 30, 60, 100, 150]
Explanation:
for cumulative sum, every index of the output list will be list[i] = list[i] + originallist[i], therefore the resultant list will be [10, 10+20, 10+20+30, 10+20+30+40, 10+20+30+40+50] = [10, 30, 60, 100, 150]
Input: list = [4, 10, 15, 18, 20]
Output : [4, 14, 29, 47, 67]
Approach:
- Create another empty list of the same size
- Copy the first element of the original list into the new list as the first element.
- Iterate the original list add the current element to the previous element of the new list and store it as the current element of the new list, i.e., newList[i] = oldList[i]+newList[i-1]
- Return the newList
Below is the implementation of the above approach:
C++
#include <bits/stdc++.h>
using namespace std;
vector<int> cumulativeList(vector<int> oldList, int n)
{
vector<int> newList(n, 0);
newList[0] = oldList[0];
for (int i = 1; i < n; i++)
newList[i] = oldList[i] + newList[i - 1];
return newList;
}
int main()
{
vector<int> list = { 10, 20, 30, 40, 50 };
int n = 5;
for (int i = 0; i < n; i++)
cout << list[i] << " ";
cout << "\n";
vector<int> cumuList = cumulativeList(list, n);
for (int x : cumuList)
cout << x << " ";
return 0;
}
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Java
import java.util.ArrayList;
import java.util.List;
public class CumulativeSum {
public static List<Integer> cumulativeList(List<Integer> oldList) {
List<Integer> newList = new ArrayList<>();
int sum = 0;
for (int i = 0; i < oldList.size(); i++) {
sum += oldList.get(i);
newList.add(sum);
}
return newList;
}
public static void main(String[] args) {
List<Integer> list = new ArrayList<>();
list.add(10);
list.add(20);
list.add(30);
list.add(40);
list.add(50);
for (int i = 0; i < list.size(); i++) {
System.out.print(list.get(i) + " ");
}
System.out.println();
List<Integer> cumuList = cumulativeList(list);
for (int x : cumuList) {
System.out.print(x + " ");
}
}
}
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Python3
def cumulative_list(old_list):
new_list = [0] * len(old_list)
new_list[0] = old_list[0]
for i in range(1, len(old_list)):
new_list[i] = old_list[i] + new_list[i - 1]
return new_list
if __name__ == "__main__":
old_list = [10, 20, 30, 40, 50]
print("Original List:")
for item in old_list:
print(item, end=" ")
print()
cumulative_list_result = cumulative_list(old_list)
print("Cumulative Sum List:")
for item in cumulative_list_result:
print(item, end=" ")
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C#
using System;
using System.Collections.Generic;
class CumulativeSumList
{
static List<int> CumulativeList(List<int> oldList, int n)
{
List<int> newList = new List<int>(n);
newList.Add(oldList[0]);
for (int i = 1; i < n; i++)
{
newList.Add(oldList[i] + newList[i - 1]);
}
return newList;
}
static void Main()
{
List<int> list = new List<int> { 10, 20, 30, 40, 50 };
int n = 5;
foreach (int num in list)
{
Console.Write(num + " ");
}
Console.WriteLine();
List<int> cumuList = CumulativeList(list, n);
foreach (int x in cumuList)
{
Console.Write(x + " ");
}
}
}
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Javascript
function cumulativeArray(oldArray){
newArray = Array(oldArray.length).fill(0);
newArray[0] = oldArray[0];
for (let i = 1; i < newArray.length; i++) {
newArray[i] = oldArray[i] + newArray[i - 1];
}
return newArray;
}
const oldArray = [10, 20, 30, 40, 50];
console.log("Original Array:");
console.log(oldArray.join(" "));
const cumulativeSumArray = cumulativeArray(oldArray);
console.log("Cumulative Sum Array:");
console.log(cumulativeSumArray.join(" "));
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Output
10 20 30 40 50
10 30 60 100 150
Complexity Analysis:
- Time complexity: O(N), to iterate previous list
- Auxillary Space: O(N), for new list
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