public class lec303 { }
class NumArray {
private int[] nums;
private int[] sn;
public NumArray(int[] nums) {
this.nums = new int[nums.length + 1];
for (int i = 0; i < nums.length; i ++ ) {
// 把前缀和映射过去
this.nums[i + 1] = this.nums[i] + nums[i];
}
}
public int sumRange(int left, int right) {
return nums[right + 1] - nums[left];
}
}