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
Note:
You may assume that the array does not change.
There are many calls to sumRange function.
我最开始用的就是把数组的元素相加,因为知道i,j嘛,可以依次相加,但是这样就会超时。
如果最开始在构造函数里面构造数组的时候就把和都存进去,这样既可。
public class NumArray {
public int[] nums;
public NumArray(