[LeetCode] Range Sum Query

声明：原题目转载自LeetCode，解答部分为原创

Problem ：

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

    Note:

1. You may assume that the array does not change.
2. There are many calls to sumRange function.

Solution：

    思路：纯属练手，代码如下：

class NumArray {public:    NumArray(vector<int> nums) {        add.push_back(0);        for(int i = 0; i < nums.size(); i ++)        {            add.push_back(add[i] + nums[i]);        }    }        int sumRange(int i, int j) {        return add[j + 1] - add[i];    }    private:    vector<int> add;};/** * Your NumArray object will be instantiated and called as such: * NumArray obj = new NumArray(nums); * int param_1 = obj.sumRange(i,j); */