Question

Formatted question description: https://leetcode.ca/all/1480.html

 1480. Running Sum of 1d Array

 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

Algorithm

In-place to overwrite, with no extra space.

Code

Java

public class Running_Sum_of_1d_Array {

    // note: in-place
    class Solution {
        public int[] runningSum(int[] nums) {
            int i = 1;
            while (i < nums.length) {
                nums[i] += nums[i - 1];
                i++;
            }
            return nums;
        }
    }
}

Java

class Solution {
    public int[] runningSum(int[] nums) {
        int length = nums.length;
        int[] sums = new int[length];
        sums[0] = nums[0];
        for (int i = 1; i < length; i++)
            sums[i] = sums[i - 1] + nums[i];
        return sums;
    }
}

All Problems

All Solutions