不是算法题，大概是考constructer的吧？？？
public class NumArray {
int[] nums;
public NumArray(int[] nums) {
for(int i=1; i < nums.length; i++)
nums[i] += nums[i-1];
this.nums = nums;
}
public int sumRange(int i, int j) {
if(i == 0)
return nums[j];
return nums[j] - nums[i-1];
}
}
// Your NumArray object will be instantiated and called as such:
// NumArray numArray = new NumArray(nums);
// numArray.sumRange(0, 1);
// numArray.sumRange(1, 2);
