Range Sum Query — Leetcode

Topic: Array
Difficulty: Easy
Question Number: 303

Problem statement:
Given an integer array nums, handle multiple queries of the following type:

1. Calculate the sum of the elements of nums between indices left and right inclusive where left <= right.

Implement the NumArray class:

• NumArray(int[] nums) Initializes the object with the integer array nums.
• int sumRange(int left, int right) Returns the sum of the elements of nums between indices left and right inclusive (i.e. nums[left] + nums[left + 1] + ... + nums[right]).

Example 1:

/Input
["NumArray", "sumRange", "sumRange", "sumRange"]
[[[-2, 0, 3, -5, 2, -1]], [0, 2], [2, 5], [0, 5]]

Output
[null, 1, -1, -3]

Explanation
NumArray numArray = new NumArray([-2, 0, 3, -5, 2, -1]);
numArray.sumRange(0, 2); // return (-2) + 0 + 3 = 1
numArray.sumRange(2, 5); // return 3 + (-5) + 2 + (-1) = -1
numArray.sumRange(0, 5); // return (-2) + 0 + 3 + (-5) + 2 + (-1) = -3

Code:

in java-

class NumArray {
    int[] n;
    public NumArray(int[] nums) {
        n=new int[nums.length];
        n[0]=nums[0];
        for(int i=1;i<nums.length;i++){
            n[i]=nums[i]+n[i-1];
        }
    }
    
    public int sumRange(int left, int right) {
        if(left==0){
            return n[right];
        }
        else{
            return n[right]-n[left-1];
        }
    }
}

Thank you
Oshi Raghav