###问题描述 给定一个整数数组,返回range sum 落在给定区间[lower, upper] (包含lower和upper)的个数.range sum S(i, j) 表示数组中第i 个元素到j 个元素之和. Note: A naive algorithm of O(n2) is trivial. You MUST do better than that. Example: Input: nums = [-2,5,-1], lower = -2, upper = 2, Output: 3…