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
Solution:
using System;
using System.Collections.Generic;
using System.Text;
namespace LeetCode.AskGif.Easy.Array
{
public class RunningSumSoln
{
public int[] RunningSum(int[] nums)
{
var res = new int[nums.Length];
int sum = 0;
for (int i = 0; i < nums.Length; i++)
{
sum += nums[i];
res[i] = sum;
}
return res;
}
}
}
Time Complexity: O(n)
Space Complexity: O(n)
Unit Tests:
using LeetCode.AskGif.Easy.Array;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Collections.Generic;
using System.Text;
namespace CodingUnitTest.Easy.Array
{
[TestClass]
public class RunningSumSolnTests
{
[TestMethod]
public void RunningSumSoln_First()
{
var nums = new[] { 1, 2, 3, 4 };
var expected = new int[] { 1, 3, 6, 10 };
var res = new RunningSumSoln().RunningSum(nums);
AreEqual(expected, res);
}
[TestMethod]
public void RunningSumSoln_Second()
{
var nums = new[] { 1, 1, 1, 1, 1 };
var expected = new int[] { 1, 2, 3, 4, 5 };
var res = new RunningSumSoln().RunningSum(nums);
AreEqual(expected, res);
}
[TestMethod]
public void RunningSumSoln_Third()
{
var nums = new[] { 3, 1, 2, 10, 1 };
var expected = new int[] { 3, 4, 6, 16, 17 };
var res = new RunningSumSoln().RunningSum(nums);
AreEqual(expected, res);
}
private void AreEqual(int[] res, int[] output)
{
Assert.AreEqual(res.Length, output.Length);
for (int i = 0; i < res.Length; i++)
{
Assert.AreEqual(res[i], output[i]);
}
}
}
}
