Running Sum of 1d Array – C# Program

Problem:

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].

Solution 1:

   public int[] RunningSum(int[] nums) {
      int [] arr=new int[nums.Length];  
      arr[0]=nums[0];
      for(int i=1;i<nums.Length;i++){
          arr[i]=Sum(nums,i);
      }  
      return arr;
    }
    
    public int Sum(int[] nums,int num){
        int sum=0;
        for(int i=0;i<nums.Length;i++){
            if(i<=num){
                sum=sum+nums[i];
            }
            else{
                break;
            } 
        }
        return sum;
   }

Solution 2:

The simple and easiest solution,

 public int[] RunningSum(int[] nums) {
      for(int i=1;i<nums.Length;i++){
          nums[i]+=nums[i-1];
      }  
      return nums;
    }

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