Range Sum Query - Immutable

Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive.

Example:

Given nums = [-2, 0, 3, -5, 2, -1]

sumRange(0, 2) -> 1
sumRange(2, 5) -> -1
sumRange(0, 5) -> -3

public class NumArray {
private int[] dp;
public NumArray(int[] nums) {
dp = new int[nums.length];
int sum = 0;
for (int i = 0; i < nums.length; i++) {
sum += nums[i];
dp[i] = sum;
}
}

public int sumRange(int i, int j) {
return i == 0 ? dp[j] : dp[j] - dp[i - 1];
}
}

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