Reccurence Notes

EQ: Sum of numbers in an array

1. Define the problem
let sum(arr,i) be the sum of numbers for arr[i] to the end of the array.

2. Base conditions
if i == arr.length-1 then return arr[i]

3. recurence reations   (sometimes it is not easy to find this, and makes reccurence hard)
sum(arr,i) = sum(arr,i+1)+arr[i]

Code:
void sum(arr,i)
	if (i == arr.length-1)
		retunr arr[i];
	return sum(arr,i+1)+arr[i];